It's an absolute cracker. I'd probably pay for it on iOS, but I'd pay more on the mac... it's really fluid and beautiful. No bugs for me. MBPi7(2.8) 13" 16GB.
Thanks! We're still having trouble deciding how to monetize exactly. We were initially thinking $4.99 on Mac. But now we're thinking maybe freemium and you can buy the remaining levels after you've completed the first 9 (for still a few dollars on Mac). What do you think?