I just got myself an Edge 200, and despite reading reviews, I had a bunch of questions that were totally unanswered until just now. Figured I'd post them, mostly just to get it all in one place for when I forget later.
I bought this thing for navigation. My current speed and such is a nice-to-have, but I'm a commuter (and wanna-be tourer) so that stuff is just not really important to me. Neither is my heart rate, obviously. If I had money to burn I would have just bought the 800 and been done with it, but I was really hoping I could get away with the 200, and I really think I can.
First off, it _will_ give you turn-by-turn directions. Not with maps (of course) but if will tell you what your next turn is and when it's coming:
That screen on the bottom actually rotates between distance and time. I don't have a photo, but it was also telling me that my turn was coming up in 6 seconds.
You have to do it properly though. It will take GPX files, but those don't have the turn-by-turn data in them. You need TCX files, which is Garmin's format, I believe. Here's a cool bookmarklet I use for that:
I can now just plan my route in Google Maps (which is nice with their bike routing), then click that bookmarklet, click the Generate Garmin Output, copy-paste that into a file and save the file as a .TCX in the "New Files" folder on my Garmin. That's going to be really nice for when I'm at home and need to ride my bike to an unfamiliar place. I was writing down the turns in the notes app on my iphone. Not ideal.
So, it's not good if you are in the middle of nowhere on your bike and you want to get home. But, if you can plan your routes ahead of time, it's great. The breadcrumb is easy to follow, and if you can make a .TCX file, the turn-by-turn directions make it even easier.