I just received '29' from PuzzleMaster this afternoon. It was my first of the Yuu Asaka puzzles (I have order '19' directly from Yuu, but haven't received it yet).
Physically, the puzzle is very high quality and visually very appealing. The solution is very clever and took me about 1.5 hours to figure out, which means it wasn't totally trivial, but probably not as hard as I expected. Luck may have played a role, but I feel like there is at least one way to solve it without a lot of cleverness or big "aha" moments.
I mentioned before that there can be subtle spoilers in the revomaze forums, and I think it's the same for puzzle review blogs. I read about '29' in puzzlemad's blog, and although he was pretty careful not to post spoilers, I feel like just the general description he had might have steered me (a bit) in the right direction. It's hard to avoid, since one of the main ways to learn about puzzles is to read these blogs.
Bottom line- HIGHLY recommend this puzzle. It's one of the cleverest things I've seen in a while, although I wouldn't say it's as hard as some have written. Assuming '19' is similar but easier, I would jump straight to this one and go back to '19' if you find this one too hard.