The demo did no justice to this game. Hopefully the bad reviews are not because of that.
Other than the rugged controls for air combat the rest of the game is great. Considering that most of the game is not fought in the air the bad controls for the jet pack don't ruin the game. There is a great story that runs through the game. In an of itself, it is a great shooter game. Shooting wise, the game is basic, but basic is good; having too many elements in a shooter can make it too much. The option to melee the enemy adds good variety to the game. The graphics are above average and the world that you play the game in is well designed.
I would recommend this game. Good story, great shooter, fun elements with the flying and cliff hanging. Overall fun and unique from the other good games.