Okay, just to be "fair and balanced", I have to tell you about 2 things that I find extremely annoying about the Treo 600. 

1) Download a ringtone, just one ringtone, and your system sounds are toast.  Apparently you have to download a ringtone manager, but neither one of the ones that are available work on MY device.

2) And if you do download ringtones without a ringtone manager, the next time you synch, they'll all be gone.  All of them.  Get Smart, gone.  Pink Panther, Gone.  Pinball Wizard, Gone.  All of them, gone. And remember, the systems sounds are gone too. 

On the plus side, it exactly fits in the Generation 2 IPod original case.