The problem isn't that it's an FF game, it's that it's trying to be new while holding onto the FF feel. Slows it down dramatically. It's obviously trying to be different, so why try so hard to be the same?
Does it have the luxury of being allowed to be it's own game? I thought that XIII-1 was tied down by the FF name and would have done better without it. The FF name brings with it some brand notice but also some unreasonable expectations from the fans. I am just as guilty at this. It is like saying I thought Suikoden Tierkreis was a good RPG but a poor Suikoden. Which it was ;)
Not saying XIII was a perfect game or that a lot of the flaws fans point out are wrong but a lot of them may have been overlooked or actually seen as a plus if the game was not weighed down by the FF name.