I played the beta (maybe alpha?) demo at PAX East today. Here are my opinions:
The gameplay seems surprisingly solid for a beta demo a month before release. There were things that reminded me a lot of the original games. One thing I liked was when your primary weapon runs out of ammo, you'll run around with it in your hand and use your hand gun in the other until you find more ammo. You can drop it to move a little faster and get some faster reload time. I liked it for the realism factor. Unfortunately, while the game felt good, I still wasn't that impressed.
For some reason, when an enemy is about to kill you, you get a chance to go into bullet time automatically and kill them with a quick shot before they kill you. I see no reason for this aside from making the game easier. They do slow motion close ups on head shots or diving shots which get old really fast. But most importantly, while it feels like a good game, there really isn't anything that sets it apart from all the other games. It's good, but I feel like it'll be forgotten quickly. I'll probably buy it when I see it for <$20 and enjoy playing through it, but there's no way I'll pay more than that for this game.