Being able to play music in the background from iDisk is pretty big.
That's one big feature it has over Dropbox, now. I pretty much prefer Dropbox over iDisk for every reason, but that's finally one point back in iDisk's favor.
Yeah, I'm glad to have this app, it's a good thing, but the music thing is still not enough for me. I happen to have both iDisk (Mobile Me) and Dropbox and Dropbox is far, far better at what it does. Places where iDisk needs to catch up and improve:
-- Still very slow and syncing doesn't happen immediately when a file is changed, as with Dropbox, and with no feedback as to which files are synced or in the process of syncing.
-- Very unreliable syncs. I use iDisk with 4 Macs, Leopard and Snow Leopard, and all have problems. I particularly love the extremely helpful messages such as 'Last sync failed' and 'Unknown error, please try again later'.
-- Can't individually password protect folders. You can either protect the whole thing or nothing, but that's it. Which makes it useless for sharing files with clients.
-- Does not keep a change history of each file so you can't revert to previous versions.