Are there a lot of people who loved XIII? It seems to get about an equal amount of hate/love but it's kind of hard to gauge things like that on the internet.
I thought it was okay, but I played it in chunks over 3-4 months, I was rarely compelled to continue with it more than an hour or two. It had some nice things about it and somewhat innovative things about it but you can say that about pretty much any numbered FF game, it just comes down to how good the execution is.
I'm not sure if I'd call it overrated just due to not many people praising it that highly but there are a lot of legitimate complaints against it.