The GPS functionality works fine without reception. It won't however show you the aerial view since it requires a data connection to download the images.
I've tried the following GPS apps for my iPhone:
- Greenfinder
- ViewTi
- Golfshot GPS
Golfshot is by far the best for me. It's the most user friendly and has the best statistics and analysis features. It's been totally accurate also on the 10 to 15 courses that I've used it on. Battery life is a concern, but if you do the following before you start your round, you'll get around no problem with plenty of battery life to spare:
- Turn your brightness down, I use about 40% and can see the screen fine even here in sunny California
- Go to Settings->General and switch auto-lock to 5 minutes, that way you don't need to deal with re-locking the GPS so often
- Manually turn the screen off when you're close to the green, and back on when you're done with the hole (which you'll do anyway as you'll be entering your score)
I also bought this combination holster/battery backup for my iPhone, for those 36 hole days:
http://www.amazon.com/gp/product/B00...ef=oss_product