That detail
That's some intense detail there, looks to me like you put some serious time into this.
I like the composition, it seems to adhere to the rule of thirds, and while the lighting seems a bit abstract it does its job and provides plenty of value. The anatomy is really neat, and I'm really digging the slight expression on the alien's face; it definitely helps to set up a mood. Not much of a background, but I can let it slide because of that nifty green smoke. I'm particularly impressed by the attention to detail you gave his head and face. That little bit of fuzz is, to me, the jewel in the crown.
I'm curious; how did you do the smoke? Did you paint it? What about the hexagons in the suit?