Yes, it's one of the worst RPGs ever created. It's almost certainly the worst big budget RPGs created. The only plus points I took from the game were the fast and fairly fun battle system and that the characters were fairly well developed (not that I liked half the characters, but that's preference).
What really annoyed me was the sheer lack of variety in the game. There was nothing to it but battles and cut scenes. It was also ridiculously linear. All previous FF games are somewhat linear but they mask it well with open areas (world maps in all up to IX), side quests (Blitzball, chocobo breeding), towns, points off the beaten path (optional towns like Gongaga in FFVII) and simple but effective puzzle elements (temples in FFX). This was ridiculously linear with nothing else to engage in.
The storyline and the storytelling is also very poorly done. The cutscenes develop the characters but only skim the surface of the overall story. To gather details of the story you have to read a datalog rather than discovering the story through exploration (as one would expect in the vast majority of RPGs, Western and Eastern). I've played FPS' where the storytelling utilises the interactive nature of game to a higher degree than FFXIII.
Reading dev logs and playing through the game it's obvious the game was a developmental nightmare. They spent years creating art assets (many of which they didn't use) and only started properly designing the game after the Japanese demo (effectively 1 year of development). Had they utilised that time (4/5 yrs?) properly this game could have been so much more.
