During Steam's epic summer sale, I picked up Crysis 2 (it's back on Steam, yay).
Compared to the originals, I found the gameplay was more integrated. The new nanosuit lacks strength and speed modes. Instead they have been merged into general use: hold down jump or melee to activate more powerful moves, and start running for speed. You can also slide around like in an action movie. Armor mode eats energy when activated, but it seems that you can take more shots with it than in Crysis 1.
I found that my favorite tactic is to run up to enemies and choke them. Sure, the aliens LOOK scary, but get up to them, and you will find that they are quite squishy and pop easily. I also like to take heavy machine guns off their mounts and use them for a bit.
There is more of a story going on than in the originals, but I don't care for it much. At first I though that this was going to end up like Mass Effect 2, but then it turned into more like Fallout New Vegas. I played on normal, and it took me about 9 or 10 hours to get through it. There were some hairy places that I needed to reload a save. Oh, and checkpoints only; there are no spontaneous in the middle saves.
The graphic options are funny. The lowest option for anything is "High". Guess they want to drive home the fact that this is a high end game (nevermind that a 360/PS3 can run it).
Crysis 3 looks like it might be cool, but it's not at the top of my list. I still got all these Humble Indie Bundles to go through.