I have a data limit of 750MB so even though my music is in the cloud I can't play it from there when I'm out and about.
In an ideal world, the phone would have 32GB which would store the majority of my tracks. In Reality, I probably only listen to a fraction of the songs I have so I can cope with 16GB.
FYI, regarding photos, if you want to keep everything Google, download Google's Picasa App on the PC. Not only is it a fairly good basic photo editor and viewer, it will auto sync all of your snaps to Google+ and Picasa web which then allows you to view them like they are on the phone via the photo app ( in the same was as with the music).
Black 330d E90 LCI M Sport Saloon Auto. Privacy Glass, Cream Leather, 6FL, I-Drive/Nav/Bluetooth, Alpine hifi upgrade.