I used it on my droid. I could barely make a whole round on my droid. However I was overclocked running at 1GHz also. I am going golfing with some buddies tomorrow and I will give you feedback than on battery life. As for the program itself, its great and very accurate.
I have used it a couple of times on my Droid. The battery will last through a round, but just barely. Probably does make sense to turn your overclock down and switch to the scorecard between shots. Mine is overclocked at 1Ghz but is set to fluctuate on demand between 400Mhz and 1Ghz.
I have also mapped a course before using their software. It was very easy to do (and free) from your computer, but took about 20 minutes or so to map out all 18 holes. You need to be familiar with the layout of the course you are mapping though as you have to map it out from a Google maps satellite image. There aren't any markings or anything telling you which hole is which, you are just looking down on the course from the satellite image and entering all that information yourself by clicking on tee boxes, greens, hazards, etc.
Another plus on Golfcard is that they are supposedly about to issue a major upgrade that allows access to course images without a data connection once you download the course. That way you can still use the software even if your data connection is slow or nonexistent.