I think he is making a mistake. As a back-up forward he is actually top-notch. But he wanted more, he got that at Bayer. Not only they play the way that suited him, they also have a decent chance for qualifying for Europe, even CL.
Right now he goes back to England, where game is more physical, and he is already 29 mind you. West Ham play in completely different style, set up, it makes more sense for them to have Andy Carroll up front or someone like him. So i think Chicarito's might kind of revert back to squad-player, super-sub type of thing. Of course WH is paying him more, that a sure thing. I wish him luck, esp against rivals, but in general, over the next 3 years, not just this next one, i don;t think it will work as well as he hopes. I don't really see him playing regularly in WH in the seasons after this one.
Actually if he would be ready to accept a lesser role, Spurs would have been a great team for him. They need a sub poacher and Chicharito one of the best in that role.