I think his new forme SHOULD look like a Dragonball character given his original form does. XD In fact, I don't know if Mewtwo did it on purpose (it's possible, Super Sonic has been admitted to be a Super Saiyan-hog, but I can't be convinced they didn't do the second one on purpose. XD)
I'm not wild about its design either, but that's to be expected of all Pokemon. XD
And who wouldn't want a Do Not Disturb sign that would blast someone if they couldn't take a hint?
PS - Mewbuu is now my second favorite nickname after Newtwo I hope lots of people nickname their Mewtwo Buu in preparation for this form.
PPS - I'm not actually a DragonBall fan just wanted to let you know because the above text could be misleading. I need to give the manga a try, though. XD