You did a great job, but the background killed the whole design. You look great, good work, did a great job on the shirt and you didn't go overboard on trying to make it too detailed.
Woulda looked better with just a solid color with a slight gradient instead of all the extra stuff. The text coulda been left out, there's too many small imperfections that stand out on it that distract me. Overall, it's decent, would of been a lot better with a 'portrait' style layout instead of all the extra cartoony stuff.