RE: Paradigms/Crystariums
I think compared to a lot of FF'ers on this board, I entered this game with a much more open mind since I only played FFX for an hour, and FF X-2/11/12 not at all. So I'm "stuck in old school FF land" guy finally booting up FFXIII.
I absolutely had no idea what to expect from this game, but I got the hang of the battle system quick enough, it's the whole switching at the right time & risk/reward (heal at the right time, or die every time) flow of the Paradigm system that I am really impressed with. Currently, I just entered Chapter 5. I've died probably 6-7 times (the Bombs killed me a few, I died at one of the early bosses, and then just at other fights where I didn't heal in time).
As far as the Crystarium upgrade system, I REALLY like that your CP's are spread over all characters, which gives you a lot more freedom (i.e. you're not stuck upgrading with a character you don't like for hours b/c you need them later in the game). And I'm fairly certain in later chapters, those will branch out more and more where you have more choices to make.
Weapons upgrading...reminds me a little of the Star Ocean series. Again, I didn't play anything between FFIX and this so maybe it existed in a different form? I think it's a neater idea than just "equip the strongest weapon you come across" from other FF's. Or do some insane time run like in FFIX for Steiner's Excaliber II (is that even possible to do with a PS2/PS3?)
So far, I am really excited about this game, especially because I just saw my first FFIX reference in between Chapters 4 and 5! FFIX is my favorite FF game.