Overall, I very much enjoyed playing this game. I'm a college student, last semester I took a philosophy of mind course and I found this game very interesting; I may even recommend it to my prof. Most of the information agrees with what I learned, but it is presented in a manner reminiscent of Alice in Wonderland (the book (whose real title was actually quite a bit longer, but whatever)). The result is a very surreal, and thoroughly enjoyable game. There were times when I literally laughed out loud at the humor (though I suppose it does help to be familiar with the subject matter, you certainly don't need to be a professor, and the THINK ABOUT command makes it accessible to nearly everyone).
There were a few negatives, though. I encountered a rather bad case of guess-the-verb with (Spoiler - click to show)the invisible unicorn and the burden of proof -- the game wouldn't accept things like PUT BURDEN ON UNICORN or GIVE BURDEN TO UNICORN -- which is quite annoying when you have a turn limit. The solution, by the way, is to HANG the burden on the unicorn, which was completely unintuitive, at least to me. Another issue is an unwinnable scenario; avoidable, though: just don't enter the castle until you feel you've solved all the other puzzles. (Spoiler - click to show)The veil is part of the puzzle to get into the castle; don't waste your time trying to find a use for it, and same for the various implements the steward will offer you once you solve her (his?) puzzle.
Because of these issues I am reluctant to give five stars, but it is an excellent game nonetheless and I strongly recommend it.
Finally, the executive summary: This is a very entertaining game with a short to medium play time, great writing quality, and a focus on puzzles over story (since the game is rather surreal, there's not much of a story, but this is intentional and done well, in my opinion).