I like it a lot. But like Doit said, it can't always be dependable. If you lose a cell signal and have already routed a destination, it will go ahead and cache that route and some possible detours. The bigger problem for me has been the phone or the app locking up. On my old Droid X, the problem was the phone locking up, then having to reboot it, which took a good 3 or 4 minutes to really get back going again. My GNex is a lot better and more dependable, but I have had the app lock up when trying to search an address. Sitting in your car for five minutes waiting for your phone after leaving a client's home or small office can be weird and embarrassing. And it's happened to me before. I ended up circling the neighborhood trying to remember how to get to the main road while the phone rebooted. lol.
A standalone unit is usually very dependable. I don't know how they are now, but usually the "connected" features require a monthly fee. Android does traffic, updated POI's, phone numbers, and everything.
So if you don't already have an old standalone, I say give the phone's satnav a try first. If you like it, but HAVE to have something reliable, figure out how dependable your particular phone is, and have the dedicated unit in your glove box or wherever just in case. That's what I do.
Btw, I want to thank you Brits for the term "satnav". It just describes it better than anything else. Calling a satnav a "gps" is just totally wrong and can get very confusing since they could mean the device itself, the software/ app, the gps receiver chip inside the device, or the gps satellites. lol, no offense Doit.
