Well, this is a certainly a well done piece, the characters look really nicely done and the expression are just priceless and really well done as well, it just gives me the impression that something is missing. Like the downright corner just looks empty, maybe make the purple "explosion" in the back be on the center of the image instead of being on the center of the kitty alone. Maybe even a huge "SURPRISE" message with the kitty but can be hard to fit right now in the image so thats just a remote possibility.

Really great image overall tho, just nitpicks to point out.