Very easy
However rather repetitive. After you get the hang of it, things just simply flow along and they lose their potency. Plenty of levels is great, though what they need is variety. Sure they have more seals and open ice areas, but these simply grow old. The problem really was the choice of gameplay and how it restricted that variety from truly coming out.
At most, change up the ice background here and there. Make something funny come out of it even if it is cheesy such as 'the seals be watching ye'.