While the Rise of the TMNT designs have grown on me, especially now that I have seen them in motion, this was made as a 'what-if', as in 'If I was to tweak these designs, what would I change?' Well, I'd probably go crazier than this, but this is basically the summary:
Raph's body would be adjusted to match his brothers more closely since the other three have similar body types anyway.
Donnie and Mikey would have more spots on their body.
Leo would have more stripes.

As for weapons, Mikey'd probably go back to kusarigama while Raph would bear a pair of jutte (which essentially looks like the tonfa and the sai had a baby). But since I know its a mythology gag/reference to the original comics, I don't mind them as much.