Michu is just a rich man's Spanish Kevin Nolan :Nolan :WestHam :BigSam
The funny thing about the Nolan comparison is while Michu is much better, stylistically it makes sense. I first saw Michu against Real Madrid last season, he got got two real poachers goals despite playing in midfield, and it reminded me of an English attacking midfielder, in the sort of Nolan/Lampard/David Platt style. You look at them and their ability and wonder sometimes how it is that they get so many goals, but they have the right instincts.
Also another less noticed aspect of Michu's game is that he's really good in the air. Not just at scoring with his head, but doing little flicks ons, and competing with big compative defenders and midfielders alike. I remember him even getting the better of Fellaini in the air which takes some doing. He's really useful for Swansea in that respect as they typically play the ball on the ground, but having a figure like Michu high up the pitch gives them other options, and he also helps defend the high ball from the opposition, which was a concern for Swansea last season when they were practically always playing with a midget midfield.
tl;dr Michu is very good at football.