Well, you CAN finish the main quest fast, if you skip several parts. If you play it with all the side quests and even take on to explore some time and not just travel to key locations, you get well over 100 hours of gameplay.

Infact, you can pretty much finish it in a speedrun way. But thats not the way you are supposed to do it.

I did lots of sidequests and then took on a step from the main storyline every now and then. It's just that I didnt finish them all because I thought I can finish them later. Thats what is disappointing me. And I dont even have any savegame before I started that last part!