Nice, but i think it would of looked better if you had of edited the brightness of the wall and made rainbow dash slightly less opaque. Here's some 'graffiti' art I've done, [link] I think it looks very realistic Oh and this is very good quality, did you take the picture of the wall yourself?
1) I kinda like the wall how it is 2) Rainbow Dash could be a little less opaque but meh. 3) I like the one you did but I kinda disagree with the style of having all the words(mainly the white part) being all solid and not a little transparent. Now, I've never really seen graffiti up close myself but I would imagine the pain being a little less solid of a color but who knows XD 4) The picture of the wall was actually from google images