I finished Fallout 4 once. I doubt I will ever finish it again. I actually rather enjoyed the game for what it was the first time. I mostly enjoyed the open world exploration and weapon customization. The settlement system was a good time waster when I was bored, though it was a very clunky system. The snap system was broken, there weren't enough building options, and bugs lowered happiness in all of my settlements. The storyline, ending, and characters were rather lackluster, but I thought Fallout 4 was a pretty decent experience. I guess it's just not you guys' cup of tea, but it's really not a bad open world shooter with light RPG elements when you take away the expectations that come with having Fallout in the name.
After I finished the game, however, I was saddened by the realization that the game has no replay value. The main reasons for this being the way the character is imposed on you, how the endings are the same, how you are forced to always build the same character, and the fact that every quest only has one way of doing it. One of the things I love about New Vegas is that it has a lot of replay value. I do multiple playthroughs each year and am yet to get tired of it. It succeeds everywhere that Fallout 4 fails, and more. As a one-time experience, Fallout 4 wasn't that bad to me. There are plenty of linear games that I enjoy.
I have tried starting a new character before, but I didn't get far. I'm doing the same things in the same way and there is no enjoyment there.