Got the Zumo 660 not impressed.
Can't lock it to the bike so have to take it with you when you pay for fuel etc.
Bluetooth phone support is cr*p. (Only old phones on Garmin's compatability list and tech support not interested in helping if your phone isn't on the list).
Firmware updates cause problems.
Bought a 2nd hand phone from their compatability list. This did work perfectly before I did an update. Now some calls are so garbled I have to redial.
Doesn't always pair since update. Takes 3\4 attempts.
Will sometimes just crash\power off since update.
Sometimes not see the sd card since update.
Doesn't remember the last played mp3 and now starts on the same song.
There have been 3 updates since I started having trouble but none address the problems.
Map can't keep up when negotiating roundabouts.
If you've downloaded custom (non Garmin) POI's these appear under "Extras" which means a separate search.
It records your route and the speed you were doing at a specific point

,
I paid £100 ish to get map updates (diferent form the zumo\firmware updates) free for life which I think is worth it.
I used to have a pda with TomTom Navigator 5 and I much prefer that software.
The Zumo 660 is not a bad idea but poorly implimented. Probably go for a TT Rider next time.