Solid facts like these?
COMBAT - Shooter combat that wouldn't have made the cut in 1998, a few things Bethesda did wrong here. First of all, it feels clumsy, the guns are all feel incredibly ineffectual and for the most part are completely ineffectual. Not only that, but Bethesda made the worst possible choice when dictating the impact of skills on weaponry, they decided to simply increase damage output and your accuracy in VATS, which is an entirely different broken feature. It doesn't make much sense, or provide much enjoyment, when you're shooting at a raider from five hundred feet across the map and missing nearly every shot at 100 skill while that raider manages to plug you in the head with a crappy .32 pistol with every single shot. So the fact that your skill in a weapon doesn't improve your accuracy outside of VATS (which happens to be completely useless at range anyway) makes the whole experience entirely idiotic. There's no being good at combat in Fallout 3, it's simply sucking less, everyone else is still better than you at shooting, they simply tend to do less damage because their magic abilities of propelling bullets faster with their mind are less powerful than yours.
There's absolutely no distinction between "good" and "bad" in the game as a whole, there's simply your level of shit and the magic aim of your enemies. The only thing that differentiates them is their health and ability to do damage. A Super Mutant is simply a Raider with higher health and occasionally weapons that do more damage. Compare this to the original Fallouts where a Super Mutant not only had better weaponry and health, but had far better skills than the average normal human being, rendering them far more accurate and vicious.
So what ends up happening? You end up being a worthless turd the entire game as far as your ability goes, the only thing that allows you to completely ruin everything as easily as you eventually end up doing is your ability to enter VATS at point blank range and shoot a few rounds into someone's head while you're invincible. That and the fact that you happen to have five hundred hit points and approximately 332 stimpaks in your backpack snuggled tightly behind your 10,000 rounds of weightless ammunition.
Yes, you're a god, but you're the most insipid god in the world, a god who relies on the game's poor mechanics and balancing to kill everything.
Oh and by the way Bethesda, developing a balanced difficulty system doesn't simply mean lowering the player's damage output and raising the damage output and health of hostile characters.
SKILLS - This is one of the more obvious ones, anyone who's played Broken Steel knows how fucking broken SPECIAL is in Fallout 3. A few people managed to max out all their skills in vanilla Fallout 3, but the realization that your characters were essentially all the same god damn thing became far more obvious when that level cap was increased. Bethesda never meant to to increase that cap, either that, or they really didn't give a shit about their half-assed RPG turning into a generic shooter once and for all. Nearly everything is maxed (if not everything), all of it at 100. The simple solution would've been simply to raise the cap to 200, preserving the Fallout tradition of forcing the player the specialize, but somehow that was too difficult, somehow the idea of 100 not equaling "the best" was too difficult to comprehend. SPECIAL never operated on the idea that 100% = 100%, it was all about tagging skills, specializing in those skills, sacrificing proficiency in other areas in order to excel at your tagged skills, and later suffering diminishing returns in order to become the best.
In Fallout 1, 100% meant you were decent, you could hit most things at mid range, at closer quarters you could pull off a few called shots, and you could typically squeeze by most encounters if you had the bigger gun since you could now actually hit anything. The percentage thing was a mistake on Black Isle's part, they really never should have stuck with the symbol since it easily confused people, what the hell is 300% anyways? Triple good?
Somehow, Bethesda didn't understand that, they decided to at last make away with the percentage, but then made the incomprehensible decision to keep it on a percentage scale. I don't understand how retarded you have to be to fix a stupid classifier but then actually end up breaking the entire system just because 100 is a "better number".
However, let's go onto the fact that the skills are all entirely stupid in their application.
Speech shouldn't alter a percentage value, once again, do away with the god damn percentage values. Speech should dictate what you can and can't say. It doesn't make any sense for a hideous stuttering retard to all of a sudden say some prophetic and intellectually stimulating piece of charismatic motivation because a tiny little brain cell in his skull suffered a massive shock that caused a neural explosion in his puny mind that granted him ten seconds of inhuman cognitive ability, or in the game's terms, you somehow managed to achieve a 5% Speech check by luck. That's not how it works imbeciles, in Fallout 1 or 2 there would be a roll to see if the option even presented itself, a person who wasn't charismatic and didn't have speaking abilities wouldn't even have the idea to think about saying certain things. In Fallout 3, this is simply all about how your character comes off, which doesn't work in any way at all.
They managed to avoid this with the Lockpick and Science skills, but really, those would have been a lot better if they got rid of the minigames, people don't want to suffer through trial and error as their reward for reaching a certain point with a skill. They want to do everything easier because that's what having more skill denotes. So the minigames are absolutely annoying wastes of time.
I can go on about how Medicine is effectively useless because of the insane amount of stimpaks you'll be carrying, how Repair is idiotic because the system itself is inexpressibly stupid and simply presents a nuisance because the entire game is already so easy, ammo so common, and enemies so worthless that all your weapon's condition means is that you'll suffer a little roadbump in your muder spree.
Really, it's so amateurishly done that nearly every skill just seems to come off as though the Bethesda developers had figured out the skill names before and were then rushing to find some method of giving it application in the game world.
EXPLORATION - I've seen games with some pretty bad prefab areas, in fact, Bethesda's own Oblivion was one of the worst, but Fallout 3 takes it even further. Almost all areas are entirely devoid of any interesting features. This is because they all look the same and use the same level cells, you can argue that audio logs and the few scripted areas negate this, but the fact is that even those areas are poorly designed. Entering the Dunwich building, I didn't even know it was supposed to be "scary" until I read up about other people's experiences, leading me to believe that the game for the most part suffers from the Doom 3 phenomena, in other words, you don't know what they were trying to do until you see other people's reactions. This goes for the Vault with the psychoactive drugs as well, and a few other areas as well. To me this presents a lack of comprehension regarding level design. They don't get what it takes, so they dumb a few "interesting" pieces of crap around the place and suppose that that will kill the boredom of prefab levels.
Combine this with incompetent enemy placement, the fact that you get almost all your best guns 10 hours into the game, the pointlessness of exploring once you've capped your level (and by then you'll have all the best equipment), and what you get is a complete lack of motivation to explore the half-assed areas in the game anyway. This denotes a complete lack of reward for exploring, versus the Glow in Fallout 1 which nets you some awesome equipment and weaponry (and access to the BoS).
Beyond that, very few areas in Fallout 3 are unique, there are a few exceptions, but mostly all of the towns feel the same, the characters feel the same (the stagnant voice acting and writing definitely has something to do with it) and the towns hardly present anything different rather than a few quests that are barely enjoyable thanks to Bethesda's still mediocre abilities at setting up intrigue and plot, maybe they should take a look at a few of BG2's or Arcanum's quests to see people do things properly, otherwise their quests will forever be underwhelming.
I could have written a lot more, but the general idea is there, this game is badly made, nitpicking is one thing, but being able to generously nitpick the entire game as you walk from place to place simply reveals a game lacking professionalism. Fallout 3 is a shoddy game, and I really doubt it's a matter of opinion to say that it isn't well made.
It's a horrible game, note that doesn't mean you can't have fun with it, a lot of people have a good amount of fun with Fallout 3, maybe a bit too much, but Fallout 3 is a terrible game, it's badly made, all of its features are eclipsed by any one of its peers, and quite frankly, it leaves such little emotional impact or feeling that in the end it comes off as a dry, chewy, and unappetizing game to anyone who's been playing this genre for years.