The thing I love the most about the FF series is that they are always different. and only you can judge them. I have had people tell me that VII is the all time best and that VIII is the bottom of the barrel. While I will say I liked VII. To me VIII was about 8 leagues out of VIIs in the right direction. I love the series.
Square Soft/Enix has never EVER disappointed me with a main Final Fantasy game, and XIII surely will not disappoint me either from everything I have seen. Judge the game for ourselves!