Took 65 hours on my first run through, and still missed a ton of stuff. I used a typical group make up (Ranger, Fighter, Cleric, Wizard)
Currently on my second run through, and at 110 hours so far, and I'm a bit more than half way through it now. I caught a lot more things on my second run through that I missed on my first run through. Different side quests, different secret areas found, so it is still very fresh. This run I did an all melee group (Rogue, Rogue, Fighter, Cleric).
Wizards are very underpowered, and actually they always have been levels 1-4. Hoping they balance back out again once the level cap is raised.