I don't mean to try to standout or put those whose GPS doesn't work well down, but mine has worked flawlessly since launch day.
I have used it with various settings enabled (including the dreaded 3G and GPS combo), indoors, outdoors, in-car, in the middle of the city (I'm from Chicago), and I really haven't had any problems as of yet. I'm most impressed by its in-car ability as I can travel 70 mph down the highway, and it is typically tracking me nearly dead on, showing me passing particular intersections or landmarks only seconds or less after it actually happens. For me, using the directions function in maps and pinpointing my position, in conjunction with a car charger, is a perfectly acceptable replacement for voiced turn-by-turn GPS.
The worst thing to happen to my GPS is an occasional delay where it can only find the large blue circle indicating my general area, and it may take a couple minutes for it to pinpoint. Otherwise, it is typically flawless, instant, and quite precise.
Also, I have travelled to Wisconsin, Minnesota, and Los Angeles for work since I bought my 3G, and the GPS has worked and helped me greatly in all locations.
Overall, my point is I love my GPS on my 3G, and not all 3Gs have faulty or buggy GPS functionality. Good luck to those of you having troubles, maybe 2.1 will enhance the overall GPS functionality for you guys?