thats awsome.
only a few things i can spot.
the guy on our left, his hand is too rounded on the left side of it. it doenst seem to have the same 2section like the bigguys hand. It looks more like an inflated rubberglove. I suggest though instead of making it that rounded, bring the edge down a bit more, and making more of a curve instead of a gradual one.
Same far left guy, his other hand goes straight into his arm. only separtation between arm and hand is his knuckles. Knuckles are only about halfway down the hand, so maby 2 pixels above, make a little indent to indicate a wrist.
Also since your lightsource is hardright, there should be a shadow on the left side of the farleft guys lips. A shadow should also be dropped on the short guys forehead behind the fingers.
The big guy in the middle now.. his hand waving looks great. But now its the opposite extreme to what i was saying with the hand and arm looking the same. HIS hand looks like one of this big foam fingers.. where it jut rests atop the arm out of proportion. I completly understand what your doing though, with the large hands small arms. I tend to do something similar in my own pieces. But now you just need to make the transition between wrist and arm alittle better. It just looks really awkward to me. (heh nice nipples on him)
Lastly, the short fatman in the back right should be darker than the rest. Since he is furthest from front he should have more of a shadow to create more of an illusion in depth.
but yepyep looks great!
i really like how you use ambient. Your dithering syle also really suits this piece, with the random circles and squares. Its great.
goodjob again