The Last Guardian not releasing. I didn't buy a PS3 for one game only, but that was the one that counted the most.
The long RPG dry-spell.
Valkyria Chronicles not returning to the PS3 and now looking like a dead IP. Easily one of the best games I've played this gen and a franchise that should have lasted.
Enslaved. I was really excited about it but the gameplay bored me to tears.
Likewise LA Noire. Perhaps the most boring game I've ever played.