I'm conducting research for the constellation walkthrough I'm making. One of the things I would like to list in the FAQ is the comparative difficulty of the stages. I have my own ideas about which ones I think are hardest, but I'd like other people's opinions as well. Vote for up to three levels you think are most difficult. If you would like, feel free to post your own opinions about what aspects make those levels most challenging, or even list the levels in your personal perceived level of difficulty. Thank you in advance for the help.

Cygnus is definately the hardest. I don't think I've gotten over like 66%! :)

Then Cancer, because getting to those small crabs is a pain once you get big...and Gemini. Because it's almost impossible to tell what's twins and what's not.

To me Cancer is a step above the other tough ones, Corona and Gemini and Pisces, because I never ever have over 30 seconds left when I make it to that wall with six small crabs, and then it's a total crapshoot whether I can even reach 4 or 5 of the six within the time left. But only rarely have I ever collected all the other little crabs to have a shot at that wall that I take on last.

cancer, cygnus, and corona for me...gemini too, but i could only vote for three, lol

i hate those levels with a passion...

I've never gotten 100% on any of the constellations, but Cygnus is the worst for me hands down. Then Gemini because all the twins aren't obvious. Lastly, Corona.

Definately Gemini for me. Gemini takes place in a pretty large area compared to the others. The twins are very spread out across the level, so it's extremely hard to finish on time. One thing that's pretty annoying for me is that different sized twins are located in the same area. For example, you have to go back to the gated town at some point in order to get the larger twins, like the town gates and clown walking on the ball. Another annoying aspect of the level is that some of the twins are pretty far out of the way (mermaids/mermen on the islands). Those skater kids around the mushrooms really bug me too because they are kind of hard to snag. Then, by far the worst part about this level is that sometimes, if I go to the town past the moat while I'm big, I'll get stuck, and twins and various other items will just start shredding off my katamari.
As for the other two that I didn't 100% as of yet, Cancer and Virgo, I didn't vote for those because there's only a couple of items that I'm missing for those two (3 crabs for Cancer and 1 girl for Virgo) that I know I'll be able to find eventually if I keep playing the levels over and over again. Hope that helps you out.