I use one as my main GPS!
Mounted on the console with a quick mount accessory kit from
http://www.gpsw.co.uk/details/prod2750.html
I used it (in good weather) to cross to Ireland and back from the Isle of Man - compass pointer to waypoint perfectly readable at a slightly bouncy 30 Knts although in true boy racer fashion it's mostly set to ground speed!
Pop it off to use on the bike, kayak, walking etc.
That new one with the wrap around looks like you can't mount it on a flat surface...
Off to the States in 4 weeks to pick up this
http://www.garmin.com/products/gpsmap478/
I just love portable gadgets which you don't have to wire in.