Performance:
This is my first pair of training shoes with minimal support since my chucks back in high school.  I was concerned about my ability to adapt after doing P90x for years in running shoes.  The transition was a non-issue, except for plyo.  Balance exercises became easier, but I can feel the added strain on my Achilles with these when doing jumping moves.  That said, it's only been 3 weeks and I already feel less strain on the ankle/Achilles now versus day 1.  Hopefully that means the connective tissue is getting stronger.

All in all, a solid shoe for P90x & P90X2; enough support to get you through your workout but allows you to get deeper into squats and work on better balance.  They're also very light, which is a big plus with plyo.

Fit:
As others have mentioned, if you plan to wear normal athletic socks with these, you might consider going up a half size.  I ordered my normal shoe size and they fit great with no socks; with my normal socks they are just a bit snug.  I actually now prefer them without socks, so I would go with the same size if I order another pair.