It's a collection of puzzles and brain teasers string today with a fairly good story. With the hint coin system, i didn't have too much trouble figuring out all the puzzles. Though at times it got frustrating because you've used 3 hints coins (the max per puzzle) but none of them give you really useful tips. Fortunately that wasn't always the case.
The art style is exceptional and i really dig it - absolutely loving the cute cartoonish look. The cut scenes are pretty neat, though i do think some of the voice acting could be better. All in all, Professor Layton is definitely the type of games where you keep telling yourself "Just one more puzzle, just one more" and finally realize that you've spent an awful amount of time in it. Well, in my opinion, that might not be a bad thing. =)
Lastly, I will be patiently waiting for the release date of Professor Layton and the Devil's Box.
P.S. I actually remembered seeing a couple playing this game (the "unofficially-translated" Chinese version) in the MTR once during my vacation.