The artstyle is really nice; consistent the whole way through, and an interesting break from the official cell-shaded cartoon version, although 'realistic' versions of cartoons are standard fare on the internet, I've never seen a TF2 female one done. The art itself is finished to a really high degree of quality and care from someone who is obviously a really talented artist, it's really really good.
However...
I agree with everyone else that the characters are just too similar to tell apart, which is kind of the whole point of the differing designs and characters that make Team Fortress 2 so unique among modern shooters.
The men are all different builds, different ages, with different quirks and styles. Their personal nationalities, hobbies, vices and quirks are all represented in their character models. Apart from the female heavy and the Demo[wo]man, these pictures completely miss that. most of them are using handguns for crying out loud, with no other weapon in sight. I'm still not sure what half are actually supposed to be, and apart from hair style they are all facially pretty much exactly the same.
As someone else said, as artwork it gets 8/10, but as fanart it manages about 2/10, it's just missing the point by making all the different classes so similar.