I'd say XCOM2 isn't that much more complex, but it gives you loads of options. The sheer number of utility items, abilities grenades, ammo types, special weapons and such means that you a lot of freedom to customize and min-max your soldiers. You can bring in 2 Sharpshooters, but one of them could be a critical hit machine with Talon rounds that uses the Spider/Wraith suit to get to high ground and deal lots of damage but is useless at close range, or you could have a gunslinger (which gets loads of free attacks) equipping Bluescreen rounds and an EMP bomb that can turn a pair of heavy MECs into scrap metal by his lonesome and put a very serious dent in even a Sectopod. Your Psi operative could be mostly a CC and support monkey, using Stasis on big targets, Inspire on squadmates and Insanity on mooks, or a nuker that can use Null Lance and Soulfire to deal a serious blow to anything in the game, or Dominate an Andromedon for loads of acid-spewing fun. Equip your stealthy Ranger with an EXO suit so that he can use a surprise flamethrower hit on unsuspecting enemies, or give him a Wraith suit so that he can pass through a wall, shotgun what's on the other side, then use Implacable (free move after a kill) to pass through the wall again to safety. The possibilities are very numerous.
The Advanced Warfare Center's random perks are also really cool. Nothing like a grenadier that has Salvo (using a grenade first doesn't end your turn) and Run and Gun, making him able to toss a grenade, move, then toss another one or fire his weapon all in one turn. Seriously, by the mid-late game most of your your soldiers will almost be using using abilities and items more often than they shoot their gun.
The strategic layer also has more choices to make, mostly in the early game. Whereas in EU satellite spam was key, here you can choose which building to go for first, when to expand, when to consolidate with relays, which rumors to pursue if there are several, which Dark Event is the most dangerous to you, etc. I am also constantly strapped for supplies which didn't happen previously.
All in all, it seems to have an amount of options easily comparable to Long War, which was a gigantic mod to a game that had an expansion, yet XCOM 2 is vanilla so far. I can't imagine how many more toys they will give us to play with in the coming months/years.