Now that is out of the way, here's my thoughts.
What I like(Can and will change)
+Increased Customization (Finally, I can ship actors and have them fight against aliens)
+Old aliens get upgrades, Sectoids are now actually a threat instead of go here and die, Vipers(formerly Thin Men) are still the bane of my existence, just they have breasts now, Mutons are more of a pain, Chrysalids are...well... can make three babies to ruin your day. Not sure how I feel about that. At least they're more brittle now!
+Gameplay finally makes sense! In the old game you're stuck with credits and have to loot UFOs to get the alien stuff. I don't get why the Council can't give you some of their looted alien stuff. Squad size makes sense, in the EU, having only a total of six guys up against twenty aliens in a terror mission filled with hapless civs was never good.
+Avenger! Finally, we get a Heilcarrier to own the aliens with! Avengers assemble!
+Possible useful abilities, like how you can chain some.
+Hacking, oh I'm gonna enjoy abusing the aliens with their own toys.
+Better canon story, original was just your typical alien invasion. Yes, I am aware the aliens were preparing you for something, but never explained what it was.
+Randomly generated maps=endless supply of maps. Some may favor the ADVENT which means you must adept to survive.
+Bradford is back! Plus new characters to enjoy. (How much longer until Shen's daughter gets unwanted fanfare?)
+Mod support! Time to add the Combine, Covenant, Reapers, and Xenomorphs to the game. Plus Deadpool, Superman, Captain America, Batman, Percy Jackson, the Powerpoff girls, and a man named Leroy Jenkins. See how ADVENT handles that.
+90% chance to hit? Missed? That's XCOM baby!
What I don't like(Can and will change)
-We lost the war, RIP effort and time I put in.
-Raymond Shen is dead, RIP you mastermind. At least we have Lily...
-Dr. Vahlen is possibly on ADVENT's side as suggested by the causal nature of how they answered that question and people speculating it.
-Randomly generated maps might be unfair, favoring ADVENT a lot more than it should be.
-Somewhat crappy alien design. Though I do like some, things like the Sectoid shows just how much badass they are now. As for Vipers, why couldn't they make it more original? Yes, I know, snake boobs might be a plus for some, but they could have had so much fun with this, but nope, snake titties it is. Muton is meh.
-BLOW UP THE STATUE MEANS WE CAN GET SUPPORT INSTEAD OF MAKING US LOOK LIKE ASSHOLES!
-Limited run time, come on 2K and Fraixs, I want a endless XCOM game where I can just blow shit up!(Might be an option though)
-Mods might remove Viper armor showcasing their assets.
-They made no mention of how they'll handle the trolls, grievers, and hackers
That's it. I'm sure there's more people can come up with. I will change my opinions once the game finally releases in Feb, 2016.