I really liked the Bon Bon Identity, Bawny Buck, and Fluttershy's Quotes, and I've seen the Crystal War Rainbow image before.
If I may ask (or suggest), if any of these official art jobs then I would mention it. For those looking for artists professionally, that speaks volumes compared to simply doing things on your own. If you've done commissions then you'd know the difference between drawing freely for yourself and drawing for someone else. I also went through your DA and noticed you were featured on Equestria Daily at least once (and I'm guessing more than that).
For feedback; you demonstrate the ability to work with a lot of concepts and methods. Cell shading is pretty good but your forte is clearly layout design. Your grasp of lighting is also very good, as is putting colors together in an image.
For constructive criticism, I'm surprised that a straight-pattern artist the ears end up with varying degrees of consistency. I'm guilty of this myself of course, but even though it seems minor, it stands out for some reason. I think it has to do with the same pose and body/facial shape of the different ponies making it more noticeable. I noticed different size and shape muzzles in a few side-by-side comparisons; they're slight, but take this as neutral, I like varying degrees of bodies and shapes in character designs.
The show-style bodies though I think suffer a little with proportions and chest or body size, but it's hard to tell if that is on purpose or not. If you're up to it, I would also suggest exploring expanding your depth of art with textures and starker shading contrasts, and maybe shading in general. You're good about it around the neckline, but some of the features on ponies like bottom of horns, wings/feathers, and etc. feel like there's a lack of light or light is coming from all directions, which puts a damper on your fantastic designs. You did it best on the badge with the deer.
From a professional standpoint, most artists who make really good money are very focused; they generally work on one art medium and excel at it. Again, something I'm very guilty of not doing, but it is an observation I've made. But I think you're more advanced in the fandom than I am, so that could mean nothing to you from a little ant like myself.
All minor things though; this is excellent artwork.