Hmm, I'll be honest and say that they could've done without Alex's vocals. Alejandro covered a bit better than Alex. Just my two cents. Overall, it's pretty great.
And also, (maybe I'm a little too whiny at this hour), they could've given ROTR a shout out at the end. I'm guessing they either haven't heard about it, or didn't bother, just because they assume that the style wouldn't appeal to their fans (mainstreamers, so it seems) :/
AND, I think what makes me like this cover is the fact that Alejandro sounds very similar to Adam from Counting Crows. I loved the Counting Crows duet with V on ATM.