I've never played a sequel that was worse than the original in nearly every aspect of it's design. Unresponsive and, at the same time, touchy controls, horrible weapon/powerup balance, cumbersome menus, jumping is a useless addition and is as pointless as the co-op mode and turret sequences, lower framerate, uncreative boss battles, and the regular enemies are nothing but bullet sponges... they were trying to reinvent the wheel in a lot of regards and in the process, broke things that were perfect to begin with. This is pretty close to Bioshock 2 and Deus Ex 2 levels of sequel disappointment for me. Within an hour of playing I was uncovering glitches and bugs.
At least Simon Viklund did his job.