I liked the idea of the Katamari concept being used with Cirno the ice fairy. It made for a really interesting, very natural combination!
The music was fun to listen to, and I liked the choice of Cirno's model.
Unfortunately, without much to roll up after the first bits, and not much to roll up towards (such as increasingly large obstacles), there wasn't much gameplay to speak of. If this was to be expanded on, I'm sure that I would enjoy it quite a lot!
Otherwise, the concept and use of theme were very interesting as is. ^.^