The atmosphere is the best part. Music, and art are all very lovely and evocative. Even the writing (though the game is short) is quite effective.
The jumping works well, but I found the wall jump incredibly awkward. I'm not even sure how to describe it. Sometimes you turn around, sometimes you don't. And when you do you do the smallest of juts outwards and stop dead. Plus it was really easy to get snagged on ceilings.
I do appreciate the real time physics of the chain dangling platforms. They didn't really present any gameplay mechanics but they were still nice.
And I think the camera over shoots when you land and then snaps back up on the next frame. Not a major deal, but if you can get it to stop a frame before it would look nicer.
I'll post my record when I upload it.
EDIT: Here it is - MM21 - The Clocktower Letter