It's not really worth it. I downloaded RR3 when it first came, but the 3.x updates really shafted it as far as fun and playability goes. It's owned by EA, if that tells you anything.
The initial promise was that you could race any car (provided you had the game money), and the last updates have locked down every vehicle you actually want to drive. They introduced "Driver Points" which let you only do a couple time trial races, unless you conveniently decide to pay actual money for more. Cars will cost $300,000, and you earn like $3,000 or 4,000 a race, then have to pay & wait hours for repairs - unless you want to buy game coins to repair faster.
And if you spend money in the game, the amount of money you get for your real dollars has also been diminished.
The in-game AI drivers smash into you, and you get penalized for it so your winnings go down. They started using a stupid point system that locks you out of races unless you upgrade, repair times went through the roof while race winnings went way down.
It used to be so much fun, too. Now, to play the game and really enjoy it, you have to spend money. And for the money it takes to finish the game at a fun pace you could buy a top of the line XBox and Forza Motorsport.
/rant. I had been racing for months and then downloaded the update and it fried. Commenting in their forums doesn't do any good because the mods selectively delete threads they feel 'misrepresents the brand.' (some members have even been threatened with legal action for it). It's so awful Apple has given full refunds to players who have spent money and been stiffed by the update.
In short, RR3 is a terrific example of Freemium done horribly wrong.