It had so much potential... but couldn't meet it.
There are tons of side missions using many weapons, vehicles, air-support, and air-strikes. There are tons of vehicles including cars, jeeps, tanks, monster trucks, helicopters, boats, etc. Hijacking vehicles is still in the game and it has been turned into a small mini-game by pressing the right buttons when prompted to hijack the vehicle. Vehicles, Weapons and ammo can be called from anywhere as long as you have money.
There are a few glitches like turrets standing in mid air. The game weapons also feel extremely weak against your enemies, it takes almost half a clip sometimes just to kill one guy. While the weapons are too weak the explosions seem too big, the explosion radius is too big and will usually affect you unless you are a great distance away.
The first game is definitely better, but for fans of the series you might want to check it out.