And the muzzle protrudes, not sinks in--it makes her nose look like that of a cat or some other non-equine creature. Instead of putting a highlight above it, try putting a highlight on it (see StaticSails' edit).
Take a second look at the source. The nostrils in particular. If I add a highlight where Static put it, it's casting light under the nose.
*scrolls down*
Then again, maybe I'm flip-flopping the persective here. I saw the line in the pencil at the top of the nose, as though we could see the jaw and nostrils and the flat surface atop the nose isn't visible. You're seeing the line as the fold where the bridge of the nose goes forward, which would mean we're seeing a lot of the top surface of the nose. Looking it the picture in the top right of the reference, you guys might indeed have the right idea -- I can't tell for sure. Either way, it would definitely read better the way you guys are seeing it.
Huh, I wasn't familiar with the terminology of banding until now, and I think I was only halfway aware of the concept. Yeah, that stretch is giving me trouble. I feel like it's where the shadow should lie, but it doesn't look terribly good. What to do? I'll fidget with it some more.
The other leg seems too thick to me too, now that you point it out. It was in the sketch too, it seems, but I guess that's the sort of thing that makes that a sketch and not a final. I'll thin it out a bit. The other anatomical problem here that's just started to bother me is that her mane only sprouts from the top of her head, and not along her neck, which is both unlike ponies RL AND unlike Hasbro's pony designs.
As for the martini on her flank, yeah, cutie marks are a major pain. I'll see what I can do, but I spent a good while failing to make that recognizable. The irritating part of these is that they're identifiers for ponies almost more so than the faces (which can look pretty similar), so to eliminate it here is to lose something of value. Making it bigger is the only thing I can think of, and meh to that idea. I'll try it anyway though.
Oh, and yeah, she's a fan character. Can't see Hasbro being cool with a bartender pony encouraging debauchery and alcoholism.