^^^^
I have to agree with the first post, its just lacking something. There isnt much going on, the backround seems very dull to me. Different Sizes can work, however if you were going to have The Rey one bigger than the rest as you have, he should have been at the front, to make it look better. Dont really get the glow around Christian, try to be consistant with everything you do, if Christian has the Glow (which he shouldnt it looks awful) they should all have it.
The first thing I do when I make a backround is render>clouds, it gives you a good jumping off point, then you can add in brush strokes and what not. Also the Boarder isnt consistant all the way round. There is a way to get around this, first save your Banner, when you have it as you want before putting on the Boarder, save it as PSD with the Layers Ticked. Then go back and combine all the Layers using shift>control>E. The go to Edit>stroke, and set the size you want, there you should have a consistant boarder.