I have - though I purchased a 'second hand' Treo 650 for Dkr 900 [= €120
= $159] instead. It works just fine.

That would be me, for one. For the most part it's fine. I'm glad to be back
with a Treo (my 600 died a long time ago and T-Mo stopped offering them; they
convinced me to switch to the Blackberry  8700g, probably the best choice at
that time. The unlocked 650s from Palm were too expensive and I didn't want
to go the eBay route.)

I'm glad to be back in the Palm world, with the following caveats:
A couple of 3rd party add-ins seem to be mildly incompatible, although I'm
hoping for an update. I used Butler and Phone Technician on the 600 to nag me
if I missed calls or voice mail, and to turn the radio off at night and back
on in the morning. They worked fine on the 600, but on the 680 it seems that
Phone Tech. causes frequent freezes. Ok, that's off for the time being, and
all seems okay there: no more freezes. The Butler nag does seem to be okay,
with no hitches.

Synching is another matter: I have an iBook and a Dell desktop and synch to
both. No problems synching to the Dell, but with the iBook every so often the
communication drops midway through the contacts and I end up with duplicates
of every entry except those that are linked to other events. Odd, huh? And a
HUGE pain. (I synch via Bluetooth on the iBook, which may be the culprit; I
haven't bothered to check out cabled synching regularly to see if the problem
is eliminated.)

(Also Mac related, not on the PC): When I try to eliminate the duplicates
from the desktop on the iBook, re-synching brings them right back unless I
switch conduit settings to overwrite the handheld. Also, making appointment
changes on the desktop creates duplicates on both, and I must use the Treo to
delete the dupe; doing so on the desktop simply recreates the dupes.

I haven't addressed these issues with Palm yet.

Still, I'm just so glad to be back on the Palm platform (didn't care for the
BB interface or click-wheel) that I don't regret my choice to shell out lotsa
bucks for the 680.

If you have any other questions, ask away.