I've got a W800i and it's dandy.
No problems with Bluetooth, syncing with iSync (contacts and calendars fine).
Everything as it should be.
Just one problem with it is the dodgy firmware. Many don't write to the memory stick correctly, so transferring music can be hit or miss. You'll copy, say, 40 tracks, unmount the phone and there are only 12 there.
SE are releasing updated firmware that corrects this - but you'll have to use a PC!
Second the vote for Dreamsicle - well worth getting that. But if you want to drag and drop tunes manually, you need to put them in MSSEMC/Media files/Audio for the phone to see them. It'll read your ID3 tags from iTunes well enough, but playlist support you'll have to use Dreamsicle for or create them on the phone.
Good luck
PS As said above, it's USB 1.1, so don't expect the transfers in a hurry!