I use the Sony T610 with my Powerbook quite a bit. Once paired, I am able to surf the internet ia GPRS, use iSync to sync phone numbers and the calenadar, and use the file exchange to send themes and ringtones to the phone.

Usability, it's about as easy as my old Nokia phones were. And actually seeing the newer Nokia phones, I'd almost say Sony has them beat now in a few ways. In general, the Sony phone has a context menu on about everything, so if I am trying to send a file over to another phone, I find it in whatever listing, context menu, send via Bluetooth. The same procedure on the Nokia 3xxx phone a friend had seemed to sometimes act like this, but not 100% of the time.

For me, I got the T68i first, then the T610 due to the size and features more then anything else. I had a Nokia 8290, and didn't see any phone on the horizon from Nokia to replace that form factor that also added features like bluetooth.