I've had a couple weeks to fiddle around with TeleNav's Bluetooth GPS receiver and there isn't a whole lot to review other than the fact that it works great. It immediately synced with my T-Mobile BlackBerry Curve which is sans GPS via Bluetooth and I was on my merry way. Of course, it didn't work while in NYC, which is sort of a given so I had to wait until I was outside of the city. I also tested it extensively while in Philadelphia for the Star Wars exhibit and then again in San Diego last week.
The interface is clean and very easy to use. Those of you on AT&T already know how easy and useful TeleNav's app is since it's readily available. T-Mobile does not have the service available to its customers, but TeleNav is currently offering the service. Say what you will about Google Maps and it being free, but it hardly ever locates me correctly. It's also slow and takes forever to load, but you can sync it with the GPS receiver over Bluetooth. I tried both TeleNav's service and Google Maps and found the TeleNav app to work a lot smoother. Everything is laid out so even luddites can figure out what's going on.
Battery life is rated at 11 hours of continuous use and while I didn't have it on that long, I can safely say that your mobile phone will die before the receiver ever will. It's also small enough that I even care it with me in my pocket. It's no different than having a pack of gum and measure in at 3.23X1.68X0.53 inches. So take heed T-Mobile users and try the service out and pick up the GPS receiver.