I was awe-struck by him when he hit that amazing run of form with Inter, but since then he seems to have been in one of the biggest slumps in form I have ever seen. He is strong and has an amazing shot on him, but the fact he is so left footed makes him very predictable to astute defenders, just force him onto his right and your sorted.
His private life is also very worrying, he is a notorious party animal, regually turns up to training hungover and if rumours are correct he was spotted in a nightclub at 2am on the day Inter were playing Juve in the 05-06 season. It was also reported on the C4 website that he beat the shit out of an American basketball player in a milanese nightclub a month or so ago.
Other Brazillians have had this problem, like Ronaldinho who at PSG regually missed training due to his partying, but he managed to sort him self out and get focused on his football. Whether Adriano could do the same remains to be seen.
His price tag would be too big for the risk involved.