In an interview with Edge, Team Ico creative director Fumito Ueda talks about how he thinks their upcoming PS3 game, The Last Guardian, will sell better than their previous titles. In a response to a question about how well well-established franchises perform when compared to original titles, Ueda sort of dumps on his last two titles.
The fact that Ico and SOTC didn’t sell well is because they weren’t good enough. They didn’t have enough to appeal to users.
Ueda, don't say that! Ico and Shadow of the Colossus are two of the best games I've ever played. I'll personally kick your ass if you ever say that again.
Ueda says that he has learned from the issues (?!) with their last products and that The Last Guardian has been created to be appealing so that people will try it and love it. I don't think he needs to worry much about that.
The rest of the Edge interview is definitely worth a read. Ueda talks about the design goals and creative process behind The Last Guardian. This info will have to hold you over for awhile as Ueda says that they're not close to finishing the game yet.
"I think I still have a long way in front of me," he says.