I have had trouble with the SMS errors. They don't happen all the time, but certain times of day, and in certain places; My schools campus has 2 locations and I get the error most of the time at one and not at the other.
My problem with the GPS wasn't with the GPS itself but with Google Maps. I was in Washington DC a few weeks ago and I was using Google Maps to give me an idea of which way to go, and it was sending me all over the place. It would lock on my exact position (within about 20 feet) but the route it would send me on was just wonky.
If you travel the same route every day, or around the same area I don't see the need to use GPS.