Here's a great comparison of the Sony-Ericsson P800 futurephone to the T-Mobile Sidekick, the past-phone whose crippling marketing decisions have cemented my intent to swap it for a P800 when my contract runs out in September. Bonus: The reviewer uses a Mac, and specifically addresses the OS X synching and modem issues with the device.
One thing you can do with the P800 that you can't on the Sidekick is take a picture of someone and associate it with their address book entry. Optionally, you can configure the phone to display the person's picture when they call. If you iSync the phone, the pictures are even carried over to your Mac OS X Address Book, which is a nice touch.
The P800 handily beats the Sidekick in the ringtones department, as you can use most any polyphonic MIDI file, or even a WAV file. I'm currently using a MIDI of the Super Mario Bros. theme song from the Video Game Music Archive…
However, as with all handheld devices, the P800's IMAP support is mangled in its own set of bizarre ways. It can't access folders other than the INBOX and completely ignores the read/unread flags on messages. Yet, unbelievably, IMAP over SSL is supported — with the caveat that your server must allow a connection on port 143 followed by the issuance of the "STARTTLS" command to begin an encrypted session. (UW-IMAP, for one, does allow this.)
One omission that seems huge is the ability to create local mail folders for sorting POP mail. You simply can't do it. You get one big folder for your INBOX for each account, and that's it. Even the Sidekick offers folder management.
