err.... it took me 63 hours to beat the final boss and every optional boss. I still have a few things to do though.

I totalled about 80 hours on my first play through.

I totalled about 80 hours on my first play through.

I have yet to complete it also.

30ish hours to complete the game and do most of those achievement bosses.

I'm only on the second disc.
It'll easily take me over 35-40 hours

im at about 80 hours and only need to finish the backyard and collect a few things.

Took me 60:35 minutes exactly to complete EVERYTHING in the game (incl. Professor K's Dungeon DLC)

Only thing left for me to do is find all items -_-

I've completed 83+ hours and I'm just into the 4th disc.  I've had many hours of unplayed time though (giving kids baths and other things).

I'll probably beat it in 40 at the rate I'm going.

I just got to disk 2 in under 12 hours. I can't comprehend why this game even needs 4 DVDs, it really doesn't feel much bigger than FFX.

Between grinding, leveling, making rings, getting skillmaster achieves, looking for all the items(still don't have them all), trying to finish all quests including all backyard battles...and then finishing the story I have over 130 hrs invested.    I didn't get the DLC either.  Oh and if you bother to take in all the dreams, it elongates the game, and they really shouldn't be missed as it's a huge part of the game's soul, and that of the protagonist, Kaim.  I read somwhere that the justification, or need I spose, for the 4 disks was because of all the cutscenes.  Didn't  seem like all that many to me, but I played the game off and on for 8 months and prolly have forgotten how many there were.

"I just got to disk 2 in under 12 hours. I can't comprehend why this game even needs 4 DVDs, it really doesn't feel much bigger than FFX."

When I completed it, it was about 90 hours with 980 achievement points. Still need one achievement (the one where you have to get every single item in the game). Haven't played the DLC. I was at the last point possible before the end at about 60 hours, then spent 30 hours on achievements.

I'm still on the first disc and am at about 4 hours. Can you still play the game once you finish the main story or is that it?

after you beat the game it will ask you to save complete game progress and you can start a new game +...warning is though it will save over you current file so you should have multiple save slots one for new game and one to go back to. 

My first time through, It was a quick run because I rented it, I spent about 50-60hours. Than because I liked the game so much, I bought it and played it again with my + save (Immortal Characters at Lv 50) and I spent over 100 hours on it and I am yet to beat the DLC boss. All my characters are level 99 and he still whooped my ass haha. 

EDIT: Oh and the Tolton's master sword being used by Kaim is just awesome!

Done pretty much every side quest and my team up to level 87 with all ultimate weopons clocking  in around 56 houts

About 70 hours, without doing side quest

I haven't beaten the game yet, but I'm close to the final boss. My save file is clocked around 50 hours or so.

I'm at around 57 hours. It definitely slows down in disc 4 when you start doing the optional quests and have to get your level up for the final bosses.