I haven't exactly finished it, I barely finished a third of "Disk 2" (or at least that's my estimation of it), since I wanted to not miss one single quest, so I have spent quite some time playing it thoroughly... by my estimations, I've probably put in around 100 gameplay hours so far, if not more... but I've stopped playing it about two or three weeks ago due to RL circumstances, I'll pick it up again after things get less hectic.
If you liked games like Final Fantasy, then it's certainly a great game for you.
The PC version is so much better than the console one, by the way, get it for PC if you have a choice.
Sure, it's also quite a bit different from the XBox versions in some of the trickier parts, so the wiki won't be quite 100% helpful - but who doesn't like a challenge, eh ? :)
The combat system is a bit weird at first sight, but you'll soon get a hang of it... the problem however is that the way the characters "learn" their skills is a bit... how should I put it... unique. There are tough choices to make, but you're not really aware of those choices until a bit later on in the game, when more options become available and you notice that the characters aren't levelling quite the way you would want them too... and then a bit later on, you realize that maybe the way you thought was wrong might actually be better in the long run... and it's a bit of a rollercoaster.
Also, some of the nicer things are almost only accidentally learned, so the wiki is quite important if you want a good enough idea of what will go on.
The characters are nice enough, even if a bit annoying at times (the "oh, come on, don't open the door, it's obviously a trap" kind of annoying usually), but the storyline is solid enough and engaging.
There are some small bugs here and there in the PC version and everything is a bit obscure since there's only minimal help (but I hear the XBox version is way worse in many different ways), but once you get used to it, it won't bother you much, and the gameplay experience is sooooo long that the initial "what the heck" moments are easily forgotten.
Oh, one thing - if you have the PC version, and you DON'T have an XBox controller for the PC (I didn't even know those existed before I played this game), you'll need to set to "keyboard hints" under the XBox controller settings in the menu, not under the "keyboard" heading. Annoying at first until I found that out (I was ignoring that section completely), so just thought I'd mention it.
It does get a bit repetitive after a while, especially if you try to "farm some rares", but that's pretty much the staple of any JRPG. It's not repetitive enough to get too annoying, since you can set your own challenge level to some degree by "chaining" multiple monsters into a single combat (for additional rewards, no less), so it's not too boring even later on.
Bottom line ?
If you like JRPGs, you should buy it.
If you buy it, I'd recommend the PC version.