For one there are no spoilers, just like in Oblivion. The main quest has no plot twists, no real "OMGWTF" moments, and yeah... It's essentially the ending you expect it to be.
The main quest has 8? main steps? I ask because it felt like there were FOUR main steps within the main quest.
I finished the main quest in 13 hours, it did feel a little abrupt at the end because
<--------- not a story spoiler, but I'll put it in spoiler tags anyway (I think this is something people will discuss when they come to it).
But then you look at your quest log, and see that there are like a hundred quests you haven't done yet (side quests). There is the college of winterhold, dark brotherhood, bards college, and like 30 other "main" sidequest AREAs. Probably over 100 GOOD quests overall, then (infinite?) stupid quests (explore x cave because you haven't been there yet).