Haze shows its hand really early in the game, so things become stale early on and there isn't much to keep you playing. You begin the game with a basic set of abilities granted by Nectar, which is sort of a steroid-like wonder drug that gives soldiers enhanced abilities, essentially making them into Supermen. Early in the game, you'll earn a new slate of abilities, though these aren't as useful as they look. For example, one ability allows you to play possum, though some enemies will continue to shoot at you even when you're "dead" - which sort of negates the point.
Nectar is more of a gimmick than a mechanic. Although some of the abilities, like the Nectar-enhanced grenade, are neat tricks, they never seem like they are vital to the gameplay. Most of the abilities aren't much different from those found in other games that managed to use them in more effective and creative ways. The only really tricky thing about Nectar is that you have to constantly administer it to yourself by pressing the L2 button and that you can overdose on it if a stray bullet hits the pack on your back - causing the screen to blur and the controls to mess up. This is the type of stuff I really would have wanted to see more of; it could have given the story that little bit of social commentary it is desperately searching for while also adding some interesting choices. Do you take a hit of Nectar and risk overdose, or try to do it on your own without the enhancement?
At best, Haze is a great idea that just never comes together. There are a few fun moments, but these don't happen nearly as much as they should and the heavy-handed narrative drags it down even more. At best, Haze is a rental, but not a purchase.