No denying James is the first genuinely world class footballer we'll have signed (from a technical standpoint anyway) in a very long time indeed, still in his prime too...but a few question marks (probably hence why we're able to get him).
Can he stay fit over a full season? How big of a concern is his lack of pace, physical and defensive attributes? Where will he fit into the team? Does he have the heart for it at this stage of his career? And so on. This could go either way - it could be an amazing signing and he'd instantly be our best player, or it could flop spectacularly and he'll be back at Porto or Monaco within a year. Ancelotti is the only manager that has managed to get the best out of him at club level which is encouraging, and of course he's fantastic for Colombia as well. It's all a question of "fit" really.