ok, in terms of SQ, i couldn't give you guys a full detailed review...
as the seller didn't include the 2.5mm -> 3.5mm jack adapter ...
but first impressions:
as a mobile phone MP3 player, i'm impressed...
comparing with K750i, the sound quality is on par, the bass might not be as good as the K750i implemented Sony's Megabass...
the speakers on it is amazing, better than the K750i...
comparing with the nano:
I couldn't tell you guys this, as I couldn't put two exact same headphones on the phone/Nano... but my guess is that, it will be much the same with some slight differences...
CONS:
bad stupid file transfer... read above posts...
and i do believe they are limiting the # of songs to 50...
bad bluetooth support, you couldn't use it as a PC remote like the K750i
only 0.3 MP camera...
Pros:
Good price
good speaker sound quality
nice display
lotsa flexibility, if you used motorola stuff, you know you could change a lot of software etc...