We've had owners of Sony Ericsson phones connecting to the service for a while but they proved to be a stealthy group of users in that nobody had ever reported any problems to us. (I'm talking about the 'home grown' Sony Ericsson phones, not the line of Windows Mobile devices they make). Curiosity got the better of me and I went eBay fishing for a test device. After a few delays with shipping and then me being out the office, my 'unlocked' P1i finally arrived today. The P1i is no longer sold, but there are similar current devices such as the G502. Anyway, the P1i is now configured and syncing. Interestingly, although the Sony Ericsson phones run the same Symbian S60 OS as Nokia devices, they ship a completely different sync client, Roadsync from DataViz (incidentally, you can get this client for Nokia devices too if you want).
My phone already had the Exchange sync client installed but Sony Ericsson's support page implies that some devices might not come with it pre-installed. Configuration was easy and I'm happy to report that it synced just fine. That is, except for the fact that contact pictures did not show up on the device. We need to so some investigation to determine why that's happening.
I connected the phone with WiFi, rather than cell data service. It does push sync over WiFi, even when the device is 'turned off'. A nice surprise because not all devices do this (the iPhone does not for example).
The keyboard drove me completely nuts. There are three or four characters per key, and both a shift and alt keys. I was unable to deduce the relationship between them by experiment and had to resort to the on-screen keyboard. The side scroll-click-wheel worked quite well though. Better than a touch interface for one-handed use, I think.
The contact and calendar apps have a good feel to them, and an initial test suggests that unlike Nokia's calendar, all day events work properly. There doesn't seem to be support for folders in the e-mail sync client (other than the inbox, sent folder etc). The device has IMAP IDLE (push) support but unfortunately so far I haven't been able to get its IMAP client to work at all. It seemed to become severely challenged by my 3600+ message inbox so I haven't had a chance to compare push sync e-mail with IMAP IDLE.
Once the remaining testing we plan is completed, we'll be adding some configuration and device-specific information to the web site.