I'll try not to come across as rude or anything, hope I can offer constructive tips ^^
1. Low quality: each fragment is low quality. I don't know whether you enlarged them or not, but you can see a lot
of pixellation on their faces, especially on Colonnello's (I don't know the characters' names, so
I'm going to use what you wrote).
2. Weird font: if you want to make a wall based on typography (examples), make sure to use a proper font. This one stands out too much
and looks too grungy, while the characters look somewhat "glossy" (based on their original shading).
Also, I suggest you place their names/roles/whatever they are, behind them. It would look better and you wouldn't
have to worry about it looking bad - I've noticed that wallpapers with characters' names on them are kind of
"static" and basic - like making a character's profile.
3. Kind of too colorful: I suggest you make most of it monocrome (black & white) and keep one color for a key
element for each image. For example, the eyes for the blonde guy on the bottom right and the flower mark on the guy in
the upper left.
Good luck! ^^