I've been playing RR3 for about 8yrs now, and even though it's been a love / hate relationship, I must say that it is very entertaining and realistic for being a phone app.
The drawbacks is that it either takes a lot of money or a lot of playing time to get cars or upgrade cars. But at the end of the day, I like it because it forces you to think about the racing line, enter speed, exit speed, and strategy.
I only have one game in my phone, and this is it. I don't highly recommend it, but if you're bored of your other games, it won't hurt to try it
Anyone else playing?