Well, for instance, in the first pic, the characters look a little flat (particularly in the head and arm area). Xiao Lu Nu's a bit hard to make out (and my best bet at her pose feels akward), and the Bleach one where you say your lineart sucks apparently needs no explaining, since you can see it. However, the one below it has similar issues (particularly the placement of the arm). Also, Ace's head feels like it's a bit too far back in relation to his neck.
As for the manga coloring, the Ichigo and Orihime pic is alright (though I don't know how crazy I am about how white you let some of the areas get), but the one you gave up on seems to have the shading trace around the characters' faces oddly. Particularly Rukia's cheeks; they seem huge, and her nose looks like its sinking in because of it.
Thanks for the crits, I really do appreciate it. I just needed to know which pics you were specifically referring to. I'm easily confused, just so you know. Just to clear up a few things though, the digital coloring technique I use has its roots in traditional coloring techniques, which is why is sort of looks hand colored.
In all honesty, I really dislike coloring digitally, but I continue to do it, because it is the most convenient. No messes, no need to buy paper or other art supplies, and lots of access to effects and stuff.
And yeah Rukia looks Arab, in the unfinished coloring
oh oh sexy bou-chan~~ <3
There's more where that came from XD