This is great! Way better than I could make,but the thing that's bothering the most is...The face!
The mouth's terrible.

Uh,that's it. It's slightly over decent.

There is no way possible he could ever go berserk.

You did a very nice job on this. I've noticed many inconsistencies in the shading, and if you put a little more attention to detail it would have been just great. I've also noticed that on both of his legs, his boots connect to his legs at a 165 degree angle, so it looks like he has a joint there, even if you intended it to look like his legs were positioned the way the boots are. His hand also looks bent. I can understand what you may have been going for with that hand position, but the way it is, directly facing the viewer, it looks like it's broken. Also, it looks like he has three fingers! As in the common anime style that I've seen has rubbed off in your drawings so much, when fingers are positioned that way they typically have only a small line between them, only a fleeting mention of separation. However, in this style, with no lines to speak of, it just looks like one finger. I would like to note his right leg (His right, not our right) has a smaller foot than the other one, even though it's clearly closer to us than the other, as well. I like his hair, too, though not very close to canon and somewhat feminine.
Nitpick nitpick nitpick.
Anyway, from what I've seen from you, you have a lot of room to improve. However, this is still great! You should really work on poses, proportions and especially backgrounds. I've been stalking your DA and every background I've seen has been either contemporary or non-existent. It would be just amazing to see you put your characters in a setting! You also seem to have trouble with facial expressions, though not present in this particular drawing. Often when you try to do something other than a smile it looks a little off-kilter, like you are only used to drawing smiles, and whenever you try to draw a mischievous smile it comes off as regular. This is probably because your drawings are very soft in tone, and a furrowed brow is often not defined properly. You should really experiment with other styles, and if you ever see a style you like, you should try to integrate a little of it into yours. I think it would really help you learn to perfect what you're having trouble with and your style as a whole. But back to the drawing at hand, before I reach the character limit. In terms of outfit design (which was probably the purpose of this whole drawing), in my opinion it's beautiful. Half of it is ripped and half of it is unharmed, which I'm sure you intended as symbolism Gamzee being half "I cAn SeE iNtO fOrEvEr" and half "KILL. KILL. KILL," which I find original on your part. His wings are also very simplistic, as opposed to the usual extremely ornate wings that people usually draw, but they compliment the outfit pretty well. They look like they were a little quickly drawn though, with a few wobbly lines here and there. Also, in my opinion, your Rage symbol is, again, simplistic, but well executed. Some areas of shading don't really match up with any folds and it looks like you just slapped them on to keep the area from being too flat looking, resulting in a kind of thick splotchy look, kind of like a normal oil painting (sorry for my lack of fluency). However, I only saw two instances of this, one of which being very minor. Try not to overlook this in the future, and if an area looks flat, it usually helps me to stay away from the edges when adding folds. But then again I don't really put any time into my drawings. You seem to put a lot of time into your drawings, though, and I should note that there are a few odd pixels to the right of his right horn. Again, his right, not ours. This may have been shine or it may have been a mistake, I don't know, but what I do know is that I by the time I'm done writing this I will have officially reached 4,000 characters. Perhaps it's because there's a lot to say about your drawings, or perhaps because I obsess over details. Either way, great job, love the design. Just remember to not rush into details TOO quickly, or your proportions will be off.

I hope that wasn't too daunting, because holy shit looking back on that this is LONG.