I have used two apps and found them to be more of a distraction then a help. Both were free. Golf Logix and Swing by Swing.
Of the 2 SBS had more features but the negatives remain the same: You spend more time inputting information then you do concentrating on the game and enjoying time with friends (or even pleasant strangers!). On both I experienced inaccurate GPS readings as compared to other apps or GPS in the golf cart or on the course. Also, frequently had problems connecting with GPS, or downloading course data because of no cell signal if you didn't do it ahead of time. Also, SBS has this social media aspect to it that I didn't need...Like who wants to track my round on Facebook while I am playing? I mean REALLY? of what possible use is this?( I am willing to admit to being 58 and not 28 so maybe thats more the issue)....If your goal is tracking your scores and games etc. then they may be worthwhile. As far as accurate yardage to the flag goes- I think its a better investment to get a range finder of some kind that bounces a signal off of the flag because that HAS to be more accurate then going up to a satellite and back.