So this game is pretty cool and simple. Make the little running guy jump so he doesn't get impaled on the spikes. The farther he runs the faster he goes. Collect rubies to get more characters, etc.
The rubies are pretty sparse, like other reviewers mentioned, considering you need a hundred for a new character; however, every so often they offer 20 rubies to watch a little 20 second ad. So, in my opinion, they accumulate at a decent rate. The irritation comes in when you buy another character. You can't pick what character you want to buy! What's up with that? It just randomly gives you some one from their list.
My other irritation is the game doesn't allow me to play music in the background (on my device). It pauses it.. And the game doesn't have a soundtrack, unless the soundtrack is silence? Strange. Not as much fun playing without being able to enjoy music at the same time.
I still like it and use it, and I'd recommend giving it a try.