A number of things that automaticaly fall on my head...
First thing, the character moves terribly slowly. He is a turtle and unlike I would expect there is no adrenaline rush to this.
Second, there is no instruction on how to change the weapon. Maybe it is just me but I had to find the right button for weapon change because without that you cannot even get out of the cell.
Thirdly, after you use up one of you pistols, at least that was the case with me, the weapon I was automaticaly switched to were fists.
Fourthly, a bug/AI fault that I discovered is in the Elevator level all you have to do is stand and the enemy will just... 'fit' into you unable to cause you any damage and vice versa. At the same time I have to note that the character cannot shoot directly down, which might be ever so slightly frustrating, and you have to be a certain distance away from your enemies in order to effectively hit them.
Lastly (from me) the recoil does not fit with where the aim is pointing. I thought I would be hitting in the same place all the time, meanwhile the bullets went all the way up...
I like the character customization, but that is not enough (fer me).
Slight correction, you may fire down, though in the elevator I found it impossible to do so... my poor aim I guess.