I'm going to go ahead and add to the anti-FFTA bandwagon...
What do you get when you take FFT, let Chuck E Cheese redesign the plot and give every character the rough power of Orlandu and Reis? FFTA sort of except there are lots of other big problems that came in somewhere!
The plot was definitely the main problem for me since that is the major reason I play most video games... WoW and NHL (year) fill my plot inept video game needs, everything else I play I play mostly because of the plot... and boy, did FFTA have a terrible plot. I find it mildly alarming anyone over the age of about twelve could find it engaging in really any way as it was poorly written, the characters were pretty one dimensional, and in general the plot seemed almost insulting, as though Square's was marketing it to a perceived Nintendo market consisting mostly of preteens.
The other main complaint I have about it is that while FFT's cultish fanbase tends to be split on whether or not they like the plot(horrible mistranslations or no), the gameplay is pretty universally considered a strength of the game and they really dumbed it down for FFTA, imo. Magic got a pretty substantial difficulty nerf and in general the characters are much more powerful compared to the opposition than they were in FFT prior to the middle of chapter 4. I don't think the comparison I made earlier to Orlandu is hyperbole at all - it is far, far too easy to create characters that are nearly that imbalanced and you can do it with generics rather than having to wait for a late game plot character! Even SCCs aren't as difficult as they used to be, although they are really the only thing that can get me to play FFTA anymore.
The Law system was pretty annoying too, it added very little to the game(and realistically if I'm fighting for my life I'm pretty sure I shouldn't fucking care if casting Fire is against the law), was pretty annoying, and since the computer couldn't be red carded wasn't even balanced very well.
All that said the game problem isn't quite as bad as I'd like to believe it is, but in being a continuation of a series containing the original FFT I had some fairly high expectations it just didn't meet. On the bright side, from what little has been released about FFTA2 they seemed to be working on fixing a lot of the shortcomings(including a complete overhaul of the Law system), so we'll see how that is when it comes out. In the mean time FFT: War of the Lions is out next week to give me something to fulfill my portable tactics needs!