I have been having the same problem. I called apple and the man i spoke to tried to make me think it was all in my head, that nothing was wrong with Siri, he even had me hold my phone up to the iphone and ask siri a question, and he said it was fine. I then set up an apointment with apple to meet with their tech guys and he said it wasnt anything wrong with my phone that Siri is on a server, he then ERASED everything on my phone and said it should work now, Siri's voice was working then, but all my apps, music and things were gone. Once i put them back on the phone Siri went back to talking like a slow robot again. I am very unhappy with this issue, even more now that I see that clearly i am not the only person having the problem so there was no reason for the people to make me feel like i was crazy for "thinking" i was hearing things! What am I supposed to do now? I got the 4s just bc of Siri if she doesn't work properly I might as well use my perfectly fine 3gs. ive tried everyones suggestions, backing up to icloud, wiping the phone....nothing is working!