He's a decent enough player and outside of his goals/assists in his first several months his interplay was decent and improving and he was generally a decent player. RVP also wasn't injured for that long in the first 6 months but Wenger randomly(as he does) decided that Chamakh wasn't a first team player and never gave him a decent chance after xmas, and the season after he joined onwards was basically shafted, like Arshavin and plenty of other players.
The two reasons he was a particularly bad buy are a free transfer meaning higher than normal wage, higher than what he was worth, meaning the MANY offers we've had for him since Wenger's been trying to get rid of him haven't come close to matching his now overpriced wage(had we bought him for 8 mil on 40k a week, we could likely have sold him for the same price a year later saving a shedload of money), the other problem being Wenger had Bendtner, who is basically better than Chamakh in each area of his game, and he was already shafting him, and Vela, and Walcott, and Arshavin and the list goes on. There was never a chance he'd be anythign other than short term cover for an injured RVP.. and we were paying through the teeth for short term cover that we couldn't then get rid of..... at a club that didn't have a "big man upfront" type available, at a club that would happily use a player like that, buying him would make sense, at a club where the manager never really wants to play a guy like that, and where we had a better player of that type, it was a mental buy.
The question of if he can do well at West Ham is, difficult, you sit on the bench for three years.... some players come out hungry and move on after a difficult period and do great, others become lazy money sapping bums who put in no effort at all(Joe Cole).
Also depends on Carlton Cole and Carroll, not entirely sure when Carroll is supposed to be back from injury, and Cole isn't scoring enough but is still a beast who can dominate defences. Will be interesting to see how many games he gets, if he's given a run I think he'll come good.