I have the Babylone and returned the Piano, the kissing cousin to the Mezzo, because the straps were too short.
IMO they're vastly different bags. The Babylone is more structured, and it has a much slimmer line. It's a bit more elegant in its appearance.
The Mezzo is, IMO, very casual looking in comparison, and I wouldn't carry it when dressing up. I don't like the wide bottom because it tends to hit at the widest part of most women, and then there's the vachetta issue. The straps are also shorter, and depending on the size of your arms, it may not go over a coat/jacket.
If the Piano's straps had been longer, it would have been a lovely casual everday bag. The Mezzo is too big for me, but then the same issues would have applied with the handles.