Meeeeh I think you're too harsh on yourself, cus your OAA is just so lovely. :3
Yea the lineart is messy looking, but I still like this a lot. x] Her lips and eyes are so nice, but I wish you added more detail to her eyes :( More thinner eyelashes for example. Oh and some parts of her vectored hair are kinda wonky wobbly. But darn you have talent, keep working at it and your future works will be amazing. @~1@
and Ithink you managed to pull off a very nice simple wallpaper. :]
+fav. for sure ;3

ZOMG it's ANOTHER WALL from you YAAAYY! xD

*ahem* Looks like I got a bit too excited. Anyways, I see that you're definitely taking a departure from your normal manga-styled walling with this very pop-art interpretation. As a wall overall, its very solid. But to me, the lack of depth in the eyes, as well as the contrast between the clothing and the hair stand out a bit too much for me. This style is definitely eye-catching, though even in pop-art there's certain factors that play off each other, so you can't keep some things too simple.

Her clothing is detailed, with a nice floral design and even a fabric texture, but when compared to the solid, simply shaped hair it's a weird contrast for me. If the hair was more detailed with more bangs and flowing strands, then the solid black color would be justified. The eyes are vibrant, but they lack a certain depth that can be added. With a wall that is focused on the face, it's important to have some sort of depth in the eyes, especially in anime art.

The background is fairly simple, a bit too much I think some would argue. But otherwise, I think her drawing a heart with her fingers is a brilliant part of the wall, and her expression is very natural. I think one of the most important aspects of drawing manga-style characters is getting the character's expression to be natural and believable, and you've definitely mastered that ability :) Not to mention that for (i'm guessing) your first foray into pop-art walling, you did a pretty good job. You've got the color choices and the basic stylization down, and all you need to do is work on the details ^^

Sorry for my second wall of text. But I really do like the wall :) I hope you got enough praise so you'll keep making art xD