From all the Nancy Drew games I have played (about 10), this is by far the hardest, and by a big margin. Many of the puzzles are extremely obscure and hard to figure out without a guide. If you like easy casual games and do not like hard puzzles that you have to figure out via vague hints given in the game, then you will get stuck and you will not like this game. Getting through this game without reading an online guide even once is a real challenge, and probably unsurmountable for most casual players.
That being said, you might notice that I'm actually giving this a positive review. That's because personally I just loved this game. When I started to play this game and noticed how amazingly hard and obscure the puzzles are, I decided that come hell or high water, I will complete this game without looking at an online guide even once. And I did.
And the thing is: When I finally succeeded, it was amazingly rewarding. I don't mean that the game rewards you with something special; I just mean that being able to figure out all the puzzles without any external help feels really rewarding all in itself.
All puzzles are solvable with logic, either using what the puzzle itself presents, or information gotten elsewhere (and most often both.) No puzzle requires blind guessing or trying all possible combinations. You will most probably require making notes or take screenshots to remember some of the info, but that's just part of the charm.
If you like hard logic puzzles and want to challenge yourself, I recommend this game. It's technically speaking very old (even for the year it was published), but that's not a big deal. However, if you don't have the patience, you will most probably not like this game.