Yeah, the last pic is pretty cool, but I think it would be better if that big dude weren't blocking out the abstract background, which looks like some kind of really cool sky. If the whole image were just that bg with maybe a few birds or some abstract creature in the distance it would be pretty awesome.
In the portrait: It's really good, but the two things that stand out most to me are the fact that the eyes are completely flat - no kind of shine that eyes are usually known for - and the nearest cheek is pretty flat as well.
The green tint makes it look kind of sickly (I'm talking about the normal colors, here) and the palette's kind of boring. Everything is so desaturated.
Also, the hair looks like it has a corner. It goes from being just vertical lines on the side to just horizontal on top. If you fixed that and made it transition smoothly and roundly, then that would pretty much fix everything that I can see right now.