While waiting for Puzzle Agent try out The Jim and Frank Mysteries – The Blood River Files
. At the introductory price of 0,99$ it's a no brainer.
I've been playing it for a bit and it's great. However, "rip-off" critics beware.. this one truly looks and feels like a lost twin brother of Professor Layton
As far as I heard, it's also very long, around 20 hours.
While I must say, I prefer the look and atmosphere of Puzzle Agent (judging by the PC demo), this one should keep you occupied until PA hit iTunes.