He got somewhat of a temper, but not as bad as people make it out to be.
Apart from the shoe throwing incident, he has been pretty much harmless at Atletico and without any controversies. A couple of years ago I'd have signed him in a heartbeat, especially when our LW and RW were misfiring big time(he can play at those positions and he has played at those positions with Galatasaray and Turkey and a few times with Atletico).
But now? For 35-41m? I wouldn't. Especially if the club want to sign Pogba(or another highly regarded midfielder) in 2016.