I think the majority of Arsenal fans can understand why he forced a move and in hindsight few could argue that it was the wrong move, but at the same time the manner in which he orchestrated his departure from the club permanently soured his relationship with the fanbase. I don't blame him for going to Manchester United, but I don't have to be happy for him either. He traded in what would have been a great legacy at Arsenal for one Premier League title, and if he believes that it was worth it then that's fair enough. I wouldn't be surprised if that was indeed the case. However, once he retires and looks back on his career, he won't be welcomed back to Arsenal nor do the United fans hold a huge amount of love for him.
He chose to be just another great player Manchester United had for a brief spell rather than securing his status as a legend for Arsenal. I don't begrudge him that choice as it earned him a solitary league title, but only he will know if it was really worth it.