Agree with the general consensus that it is unacceptable for a player to swap shirts with the opposition at half time. I find it both disrespectful and unprofessional to be doing it when there is still 45 minutes left to play, never mind your own team are three goals down. You should still be in game mode throughout the 90 minutes including half time, at the end of the game is the time to shake hands and swap shirts if thats what you're into.
Balotelli has done himself no favours. Its a little bit amusing as everyone was laughing at Arsenal for buying Welbeck when they could have got Balotelli, on retrospect they have made a decent signing.