I originally got this game as a child in 2006 but never completed it, ad I finally got to finish it almost twenty years later, so keep in mind that I might be biased in my review.

First of all, I feel it's worth it to specify that Keepsake is not a point-and-click game in the usual (Monkey Island/Sam & Max) sense. Here, the only points of interaction between the player and the world are the puzzles, and therefore I'd be more inclined to categorize this game as puzzle adventure.
The puzzles are the real strength of this game in my opinion, going from being trivial to requiring some serious brainpower (I'll confess I threw in the towel a couple of times, or maybe I'm just stupid, go figure). I'll say though that the concepts behind a couple of puzzles required me to make use of the hint function (there's four levels to it: the first three give you progressively more useful suggestions while the fourth outright solves the riddle for you).

The second big thing Keepsake has going for it is the atmosphere: the grandiose setting combined with an evocative soundtrack really make the game stand out despite it being quite generic in terms of medieval fantasy. The story could have used some more work, as I felt it was a bit too rushed especially at the end, however the characters, at least the main cast, I found to be quite well-written.

On the more technical side, the graphics and voice acting I feel still hold up to this day (for the voice acting I'm referring to the Italian one, just to be clear).
Some of the game's features, though, feel quite unpolished. The "skip dialogue" functionality, for example, just skips the voiceline/textbox but not the animation, which you'll have to wait for in awkward silence.
Speaking of polish, the game suffers form quite a few bugs that mainly cause it to crash to desktop due to memory leak issues in some areas or during some puzzles. This, while annoying, can be circumvented by saving often or by using the unofficial patch.

Lastly, a little bit of a neutral heads-up: the game requires A LOT of backtracking and going back and forth between the same areas, which can be annoying to some.

7.5/10 - I think it's worth it if only for the observatory puzzle, IYKYK.