An above average game with a lack of enthusiasm.
That doesn't mean it can't be a great game. It's really good. However, there is just something missing - and I don't really know what it is.
The singleplayer game is long. This can be a good thing. However, it does feel a bit repetitive. It's an FPS though...so you may ask what kind of variety can you get? Well, when I play the SP campaigns of Modern Warefare, Modern Warefare 2, Battlefield Bad Company 2, etc, I don't feel like I am repeating the same things over and over. Sure, it's pretty similar, but you get just enough of something else to take your mind off of it.
You don't really get that with Crysis. The breakup comes in form of stealing a vehicle and flying down the road shooting at stuff. There are even mission endings where you hop into a mounted gun on a vehicle and start to drive away (scripted) and you think you're going to be having a battle...but then the mission ends. I can remember two specific places this happened. This game doesn't lack polish, but it lacks the final coat of wax.
Secondly, the enemy AI is typically horrible. Routinely you will find them full sprint into a wall and continue moving their legs. Easy stealth kills.
Other times however, the enemy is almost cheap. They seem to have a 6th sense of your position while cloaked, especially the big "boss" guys you have to shoot with a rocket launcher until they die. Another drawback. It's kind of old and boring to play missions where you have to run, get some sort of ordinance launcher, shoot the enemy in the weak spot, find another, rinse, repeat. Maybe some people enjoy this mechanic, but for a game that came from open world and insane graphics, the fact that at some moments it reminds me more of Lost Planet 2 is definitely a bad thing.
I DO love that you can play the game your way. Except for a few moments in the story, you pretty much have your stealth and armor abilities and can use them as needed. This is nice because it can totally develop into a new experience. You're not forced to play parts a certain way or only using one of the abilities. The game does suggest you to equip them in some instances, but mainly armor, and it's used to protect against dying after longer drops.
The last mission is probably the most irritating. I played stealth the whole way through the game. It was fun, challenging and my personal style preference. The fact that you have to kill all the enemies in the final area doesn't really mesh well with the fact that leading up to that moment, and in most other missions, you can bypass entire squads just by cloaking and running through them.
I did appreciate that they devs allowed that, however. Sure it may be "cheap" but I didn't want to have to fight every mounted machine gun, and kill every grunt. I loved skipping battles where I was easily outmatched, because I felt that would be the most realistic way I would handle it given the same situation. I really appreciate the devs allowing us to mold our experience. I just wish the game seemed balanced the whole time.