Shank 2 improves upon its predecessor, but creates a bunch of new problems.
The Bad: Stupid story, bad voice acting, very short, lame bosses, extra combat abilities feel useless
Shank had a great idea, but was poorly executed with extreme difficulty, sluggish controls, and monotonous combat. The story was interesting with lots of gore and boobs, but there wasn't much beyond this. Shank 2 tones down the difficulty a tad, improves controls, and adds a few things to combat, but the story this time is lame, the voice acting sucks, and the game is even shorter. How Klei screwed up the sequel so much is beyond me.
As Shank you still have your shanks, but there are a few new weapons. You can use molotovs and land mines as projectiles this time. The sledgehammer is a new one, but you also get to play as Corina for one level and she has her own weapons. I would have liked to see more new weapons, but if you count the turret sections then that could be a new one. The combat is exactly the same as the last game, but the controls seem to respond a bit more and that annoying knockback effect isn't in effect as bad here because you can at least jump as soon as you get knocked back. The pick-up button is no longer the dodge button so you can save your tequilas for when you really need them and not accidentally drink them.
My main disappointment is that the boss fights aren't as interesting and are pretty easy. They all play out the same, and the final boss is a cakewalk compared to Shank's final boss that was a serious pain. There are some environmental elements added where you can press buttons and certain things will damage enemies or open traps. This can help you in a pinch when you're surrounded. Weapon pick-ups are a new feature, but most of these are useless except the large ones, and this includes large items that can be thrown.
The levels seem a bit shorter and the game can be beaten in just a few short hours. Besides the few combat changes, the game is actually worse than the first game due to the stupid story, and disappointing bosses. The visuals are still great with lots of gore, but the fundamental problem is that you're just hacking away at the same enemies through every level. I would have liked to see more platforming sections, or some scripted events, but those are very rare in this game.
Overall, Shank 2 is a fun game to go through thanks to the lowered difficulty, but you won't get the same satisfaction when beating tough and interesting bosses. The combat and controls have been improved a lot, but the newly added elements like weapon pick-ups feel almost useless. The story is lame with bad voice acting, and the game can be beaten in a few short hours. Fans of the first game (the few that there are) should go ahead and pick this up, but people who held off on the last can skip this one too.