The game maintains that high quality throughout. There is some variation in the monsters as well, though they all follow the same messed up corpse theme. Some are big, some are fast, etc. There's enough variety to keep it interesting.

As for ammo, you'll have plenty. In the beginning you're a little short, but it ceases to be a problem after awhile. You can buy ammo from the store terminals and enemies drop plenty. A cool thing about the drops is that they drop ammo for whatever you're carrying. So you don't get stuck with ammo you don't want. You can carry four weapons and if you're only using two you can just sell the ammo for the other two that you'll find and buy what you want.