The free version of my Golf Solitaire app just reached a nice benchmark: 10K active installs. The retention rate is between 35-40%, which means about a third of the people who download it keep it on their phone for an extended period of time.
Spades Free actually has more active installs (close to 25,000), but GS seems to be gaining momentum and performing very well. I'm also happy with the conversions from the free to paid version. Sales of GS increased by about 30% from August to September, and so far this month they've gone up even more.
October looks to be a very good month already, and that's even before any new Android phones have been released.