Spoilers from Vella's part of the game.
After finishing the game, I must say I have enjoyed Shay's part a lot more. It felt tight and fun, while Vella's part felt a little tedious, long and confusing. While on Shay I knew every minute what I should do, but on Vella I was pretty much confused most of the time. Her "mission" wasn't as clear as Shay's. When I reached the clouds, I just started wandering around, not feeling that I should return. Vella should mention again that her family will be dead if she won't go back fast.
After leaving the clouds, it is possible to go back there, probably because of the Riddle of Yorn, but so many screens and options left me confused. The Riddle of Yorn is unrelated to the clouds, even though you have to go back all the way there to find the answer. I am lucky that I had it with me already.
The most confusing part about Vella was helping the mayor. I virtually gave him the sap just because I had a hunch. I did not understand at all that he wanted a way to make the sand stick.
Maybe a small map should be added to the Vella part, to make travelling to the clouds and the sea a lot faster.
Vella should mention from the moment she get to the clouds that she must go back now before Mog destroys her village.
And making the mayor part a little more understandable: He should mention more clearly that the sand won't stick together.