i like the style, but some critism if i may, its a bit to small in my eyes. sure its minimalistic but you would need to know what is what, but a touch bigger wouldnt hurt would it?
some ideas that just came floating:

- a target modelframe on top of the targetframe(if that is the targetframe) with a 1 pixel border around the frame would make it nice.
- another texture for the health/mana bars to give it a more appealing view.

the rest is very nice. keep up the good work!