The main thing I've noticed people complaining about is the fact that instead of just giving you rather loose objectives and letting you solve how to do them yourself, the game insructs you in the various options you can take. That takes out a lot of the fun for me.
Also the setting just blows, I liked the jungle.
I haven't really noticed the thing about not giving you loose objectives, from what I've seen they give you at least two or three ways to do something. They certainly don't tell you how to do it though.
Personally I prefer the city to the jungle, I'm not sure why I just felt as if the island wasn't inspired. To much of a look back at Far Cry.
One thing you might not like about it is how streamlined they've made the nanosuit now. From what I've seen there's only a armour mode and a stealth mode, and strength mode only gets activated whenever you do strength things (like holding spacebar to jump high, etc). But on the flipside of those changes they've also made the nanosuit customisable by using "alien tissue" or some such to upgrade things and unlock new abilities for your nanosuit like being able to see bullet trajectories to dodge them, or make your armour mode last longer, etc.
I'm liking it.