Klei Entertainment's Shank is a good game. I want to say that first. It really is; I enjoyed it. But it's such a good game that it was painful playing through it, noting all the things it did that stopped it from being a great game.
When I finished Shank I noted sardonically on Twitter that either nobody at Klei played the game, or they hate their players. My core problem with the game, and primary source of frustration, are the boss fights. I had a wonderful time with bosses in Noitu Love and Noitu Love 2 (games created by one artist/designer), and it was frightening that Shank's bosses were alien in comparison.
A good sidescroller boss is hard to execute, but the concept seems pretty simple. Challenge the player's skills in a unique way, and have the player fight through stages.
Noitu Love 2 had some great boss fights that had the player jumping around activating things, surviving barrages by dodging and then attacking weak spots, learning patterns, and skillfully attacking at the right times.
Shank makes a cardinal mistake with all of its boss fights in punishing the player for fighting -- the boss fights seem far removed from the rest of the game and, counterproductively, are less fun.
A boss fight in Shank has the player avoid the boss until he enters a "I fucked up, and am vulnerable" state where the player will then press the right trigger to do damage. Rinse and repeat. Any attempt to use the game mechanics against a boss character produces punitive results. I get the idea that bosses are supposed to be intimidating, but killing me for slicing, shooting, jumping, and grabbing against a boss in a game all about these things is a mistake.
The final boss battle had me doing a few strange things, and epitomizes the rest of the boss battles. The fight is comprised of three stages, breaking up the boss's health bar. The player is instructed that the thing to do is block at the right time to damage the boss.
Problem number one: I never had to block much in the rest of the game, and the FX don't read very well. I'm still not sure if I'm supposed to block at the moment of attack, or if holding block will work -- I spent an hour with that boss, and I couldn't tell which was working.
Problem number two: The natural way to beat the boss was to attack him and block when the opportunity arose. I felt like I was playing the game wrong by using the game mechanics in a boss fight.
What I ended up doing was interesting. After many failed attempts using block and being hit for massive damage in stage one of the fight, I started a war of attrition. I would dodge quickly to the left and right of the boss, using my weakest melee attack - this helped since he would otherwise always block me, and would often launch his attacks on the side I wasn't on at the time.
Any time I used a gun or a heavy melee attack I lost about a third of my health, so I stopped using that half of the game. I proceeded to use my dodging trick and would mix it up by backing away and doing jumping slashes, or by throwing a grenade and then following up with a quick slash.
I got it down to a couple minutes on the first stage. Cue skippable cutscene that appears every time, and stage two. The thing about stage two, is that it's stage one. So I did the same thing there. But either the boss gets a bit amped, or I would get a bit tired, and I would often die and have to start at stage one again.
An hour later I was at stage three, where I hit the boss in the corner and then hit him again, knocked him down, then kept hitting him. I spent about twenty seconds or less on the final stage of the boss fight, which was followed by a cutscene made disappointing by an hour of rage.