Damn fine game, my friend. This has a definite Myst/Riven vibe to it, and it there were even subtle reminders of later Submachine games. You pushed past a lot of top escape game creators by using a semi-3d engine with smooth transitions, and the hidden notes added a little of replay value. The visuals are lovely, the music is relaxing, and the sound effects are perfect. It's nice to see an intriguing setting with a laid-back atmosphere instead of that creepy feel some many programmers go for (and sometimes fail to invoke).
The only criticism I can give is that the puzzles are simple and the game is pretty easy. But it didn't take too much away form the experience since A/V aspects of the game were so satisfying. I just found it enjoyable to play. Also, if you can, try to make every square capable of exploring with the spinning/directional arrows. It will feel less awkward than having them appear only sometimes, and it'll increase the immersion if the player can look around from any location.
As a suggestion, you might benefit from adding a little more story. The notes are good, but all they do is discuss the explorer's sense of wonderment, which we can sense for ourselves by looking around. In the future, consider using such notes as a way to tell the previous explorer's story, or reveal things about the ancient civilization that we aren't seeing. And consider how the writer thinks; would he really be surprised to see lasers after moving through three or four apparently magical gates? (Sorry... just the author in me talking).
A good game. I may have to download the extra levels.