I've been using Swing by Swing for a couple of years and I really like it. You can use it for GPS distance measuring and scoring - which seems to be more battery efficient than having two separate apps. It's about $10p.a for the full featured version or free for the basic version.
The GPS distances seem to be very close to those conjured up by my friends' SkyCaddie and Garmin devices. Certainly within 3 or 4 yards which is easily close enough for me!
If you buy some NFC-tags, you can even turn your phone into a GameGolf-alike, for a fraction of the price (I haven't tried this though).