Please take no offense from this. If you must, go to the bottom, where I graded it. ^^ I notice I tend to leave out the good things in my criticism, so I gave you a grade to go by so you know what I REALLY think!

This other stuff is just some advice on the suit itself and some of the shading elsewhere.
Suits are hard, believe me; my own suit-wearing-doll gave me so much trouble that I was ready to give up.
Here's some advice; suits have a lot of almost choppy-like fold. Use the pics in the link Kitty provided in the thread; they give you an idea, somewhat. You can also look up pic-references for tuxedos, cus they do the same thing.
Also, suits have
very angular shoulders, to perhaps you ought to exaggerate that a bit*, especially with that pose; I've worn a "penguin suit" before, trust me. XD The square shoulders sort of poof up but remain square when you pose like that. O.o (I wore it for band, and the coats are HEAVY! But our outfits look more military than suit-ish, so there might be a slight difference.)
The asterik just means that it's optional; I can see you did make the shoudlers angular, and it would be more caricature(sp?)-like to exaggerate. ^^; If you are offended by this, ro whatev, thne ignore my ranbling!
Perhas you could use darker shadows with the white ribbon on the hat, because the black sort of kills it, and you coudl d the reverse with the black... let there be light! Don't be afraid of contrast; contrast is an artist's best friend! ^.~
All in all, if I were to grade this in it's obviously rough stages, you'd get high B+, low-midle A, most of it for design. Don't be afraid to play with it a bit, and be bolder with your shading and folds; soft and mild works for cotton tees, but not everything.