Already having the first three games, I was going to pass, but Alchemy Mysteries had me interested. Didn't have time to give it much thought, but it seems to be more than the usual casual game. It has lower than average reviews on BigFish precisely because it wasn't the "same old" hidden object game familiar for most people there, apparently being much closer to a regular adventure game.
It has 360-view, exploration and regular adventure puzzles that can apparently be quite challenging, little hand-holding to speak of (but there's also casual modes with hints etc. for those that want them), and the hidden object scenes can be skipped if needed be (but they also seem to be much less of the "clutter the scene with all kinds of random objects" type, being more cohesive, sensible environments to explore, at least from what little I've seen and read).
So a heads-up for the adventure gamers to maybe look into this one, as it seems more than meets the eye. Anybody out there that's actually played it that could confirm or deny?