Yeah the cloning mechanic was really well done, and also really impressive all the systems interact flawlessly without any bugs at all. Really good stuff.
And for the record, when I say it was my least favorite, it's like a 7/10 and i still liked it, just a little less. I enjoyed pretty much every level to some degree :)
To me the portal maze felt like a little break, , since it was pretty easy and a bit different than the more traditional puzzle levels. It might work really well if it was a recurring bonus level where you can get a little reward for good luck, if there were any ideas for powerups or special items.