I disagree, I personaly think that Casillas is one of the top 3 goalkeepers in the world. But you are right about Madrid tho, they buy the best and most famous players, and that, IMO, only proves his worth, as if he wasnt good enough he would have been replaced years ago by a more prominent goalkeeper, a Buffon, or Kahn, or Toldo...
IMO he's been one of the better Madrid players in the past two seasons, and in Spain he has Canizares as competition and the fact that he's keeping him on the bench is another sign of his quality. I've seen him play live against Bosnia twice, and I can tell you that he's always been great, in those two macthes we played some excellent football, but only got away with two draws, thanks to Iker who saved them more than once.
I personaly rate him very highly.