Ok... you guys are both friends of mine, so I'm going to be completely honest with you. First of all, I've never heard this song before, so I'm basing this purely on a cold listen.
You were both pretty flat on the solo parts. When you started on the 'harmony' part, Crystal - you were singing an octave instead of harmony, then you DID switch to harmony. Now I don't know if that's the way it is in the original or not, but I thought I would let you know. The octave didn't sound bad, but when you hit the true harmony, you both sounded really good. The harmony section was the best part of the sub.
I'm not going to say much about tone or anything else, because you guys are both good in those areas. Your only problem with this sub was pitch.
Good job on nailing that harmony toward the end though! I know this was your first attempt Crystal, so way to go! Harmonizing can be really hard to do and if you don't have the right kind of voice for it, it just won't work!
Hope I didn't hurt any feelings here...
You know I love you guys!!!