It is a LOT of fun. The humor is just right, not subtle and not in-your-face please-laugh-at-this-joke.
It is extremely frustrating (in a good way) to get your spell elements in the wrong sequence, or fire them with the wrong button, to see something completely different happen than what you intended. And that's the beauty of it.
I think my favourite spell is the one where I summon a stone around me, like a personal shield (shield+earth+selfcast). It allows me some precious time to sequence and boost my next spell, without getting interrupted (the rock shield takes a ton of damage). The only downside is it overwrites a personal (shield+self-cast) which is your basic defense. The rock shield, and then you load up on a ring of mini-volcanoes around you (fire+earth+defense+AOEcast) = win.
At 10$ or 10€ this is a bargain, a must-have. They could price it at 25 and I'd still recommend it.