Lovely Bishie Spotted! and it's Yone Kazuki's bishie! (/x3x)/~ <3
I like the overall impression of wallpaper but I can not say the Vector "neat and clean". There's lots of jaggies and jpg artifact in vector, which is ruining vector quality. :/ The color hasn't filled precisely leaving some empty pixels here and there, and which upon saving on "jpg" format image, made thos empty pixels white, and their around space jagged.
The best part would be Sano's hair, and use of gradients, but still I feel like there was no need of the dark color blob from where is bangs are falling, I'd used a vector shape with dark color there.
And skin, bedsheet, curtains, ribbon etc have no gradients? just solid color fill. Yone kazuki's coloring style is very complicated; it may take hours of work to accomplish something like her level. Being her fan, I tried many vectors of her art, but never been able to finish even a single one. xD
So yeah, adding gradients may make everything look more lively like hair here.
And definitely some texture/patterns on curtains. They are looking flat dunno why... Also on a new layer add some dark color (black?) on curtains which are away from main focal point (Sano) and then blur that part, play with opacity/fill to get a desired "depth". Our Lady Val'sthis wall is perfect example for reference of giving depth on BG curtains.
Keep it up! and yeah try saving your walls in "Save for web" option and increase the quality level to 100% this is lessen the amount of jpg pixelation.