Just beaten Prototype 2. Felt more mainstream compared to the first both in good and bad ways. It's more polished but has less freedom to customize the main character, controls and movesets are similar but there's some tweak, you need no grind but it ends in 8/9 hours (client says 8, web says 9, in the first one I've spent a lot more time) even doing a bit of side missions, no particular threats from enemies and last boss is much easier.
If you liked the first one, the second is at least interesting to play.