So, this has been on my iPhone for about 10 months now, and I've played it most days in that time. I've only just completed the last of the 366 puzzles (you get one a day, but I was so addicted for a while that I messed with my phone's clock to unlock them faster), and according to the Game Center leaderboard that's taken me around 15 hours. Pretty awesome value for 69p.
Now waiting for the first batch of extra puzzles to become available as an IAP (the developer said in an email today that they're in final testing) and I'm hoping its soon or I'm gonna be jonesing for my daily fix!
If you enjoyed the substitution ciphers in Hundreds, then here's 366 more, but with a far more user-friendly interface for solving them, and answers that are classic movie quotes rather than obscure riddles.
I honestly can't recommend it enough!