I too have this game, and while it is charming, somewhat relaxing, challenging, with an interesting method of narrative, it is also monotonous and slow at times, so I have mixed reviews so far. I guess it gets a thumbs up from me and I would advise others to play it, but with those few caveats.
I think I am 70 or so puzzles into it, and have d/l'ed another 3 or so, one of which I find impossible.
Some of the puzzles are ridiculous (both hard and easy) and some are just downright lame and illogical. Sour grapes? Maybe, but I don't think so.
My aunt (Susie) played through it and solved all but 3 puzzles she said. She also said the story is interesting, though I may have figured it out (mostly) by watching a certain cutscene that mayhaps offered too much information...
Besides that 3:33 puzzle, which I needed a pencil and paper, I have found that the rest of the puzzles (that I can recall) usually rely on some form of misdirection and informational red herrings. Some seem like you need algebra, and then end up being the most obvious answer that needs no mathematics at all.
All in all, good stuff. The more I talk about it the more I want to play it! So, I guess my review has been bumped up from a B- to a B+ in the span of a few lines of text!