This is very striking. The contrast between warm and cool colors, and the dark and light values cause the phoenix to stand out quite nicely against the background. Also, the composition of the piece expresses a nice dynamic feeling; the wings' positioning, feather bits, and the tail's placement gives a sense of motion and establish the phoenix's power The placement of the phoenix on the right and the decision to leave open air on the left (rather than just crop at the wingtip) adds a lot to the dynamism as well.
Despite really enjoying this piece there are a few things that bother me a bit and since I don't see the point of a critique that does nothing but praise I thought I'd explore them. One thing that confuses me a little bit is the lighting on the phoenix; The feather bits seem to emit their own light and it seems like there is also a light coming from below the phoenix but the wings have very little light on them in comparison. Compositionally I think this contrast works but I can't help but wonder about it anyway. Also, the tail feathers seem a bit like they're squashed into the canvas and that they are coming up higher than the angle of the bird make it seem they should; The wings angle makes it seem like it's moving a bit more upward than the tail feathers imply. Just a few observations I had.
Now THIS is impressive. The subtle amount of realism blends really well with the style.
The details on the feathers are super nice, especially on the chest. That's my favorite part about this piece: it's very textured and very detailed. I will comment that the right wing seems less detailed than the left, or it maybe was a little bit over-glowed.
This may have been due to stronger glow on the right wing as well- I feel a LITTLE bit more warmth on the left wing would have been welcome, just to be a tad more consistent, and to improve the lighting. (Not too much more: i get a feel of left-to-right/near-to-far bright-to-dark for the piece, so you obviously wouldn't want to remove that.)
The flecks of fire are very varied for just being ember and ashes, which I like a lot as well: it keeps things moving without drawing the eye away from what's important.
I can't find any fault with the motion: it's got a solid direction and is supported by the colors and contrast, and for the anatomy, I'm not sure how phoenixes are specifically shaped but the only thing I can say is I think her legs may be a tad short. This is relatively minor, however.
It's hard to find a lot of things wrong with this piece so I'm not going to make up issues. There is some stuff that could have been done differently, just to get a different effect: as is, Philomena contrasts well with the background and pops out, but the image feels very cool against the blue. Dabbling less into the greens and more into the pinks and violets for the background may have made the piece stand out with warmth, suiting for a firebird, which might have been a neat route to take. (Again this is just a suggestion, something I just think might've been cool as well, and doesn't really have an impact on the piece.)