[Closed] What simple but good 'turn-by-turn' GPS for riding?

Apologies for a possibly dull and overcooked thread, but now I'm discovering a whole new county on my bike, I've woken up to the fact that a bar-mounted GPS may well complement my trusty OS map and pen route-finding. Specifically, it may drastically reduce the number of crazily steep hills I whizz down having missed a vital turn, and then have to (stroppily) winch back up to get back on course!

Now, there are plenty of iPhone apps that will show a gpx route on a map, but there doesn't seem to be any sat nav style apps that provide turn by turn navigation akin to driving ones. There is of course the issue of looking like a bit of a Herbert riding along with your phone stuck on your bars. (No offence intended towards any Herberts out there.)

So it seems it's got to be a seperate bit of (new-better-faster-obsolete?) electronic kit. I'm not fussed about power metering, heart rate and cadence counting etc. I'm just after the above-mentioned ability to load up a gpx file, and then have the navigational cues before I fly past them.

What does the greater STW posse use, and how do you rate them?

Cheers!