I would not have minded if Bethesda made a smaller game with better content than a huge game like Skyrim with somewhat repetitive content.
The majority of quests go something like this "Find person X, who tells you to go to ancient ruin Y, fetch artifact Z while fighting off hoards of level-scaled undead, and bring artifact Z back to person X for money." Rinse and repeat.
I was extremely disappointed in the Main Quest. I found myself postponing parts of it simply because I was too bored with it. It didn't have the sense of urgency that I felt it should have. Somehow, I managed to find the time to start the Companions and finish the Dark Brotherhood, College of Winterhold, and Thieves' Guild questlines and many
Daedric quests before I felt like saving the world from impending doom that could wait one more day.
I also found dragons to be lackluster. They used the same set of moves, were rather predictable,and simple to counter. They simply didn't pose the same threat as a giant, mammoth or even a bear at times. The thing I found most disappointing with dragons was that the final boss of the game, a dragon, behaves no differently from the random-encounter dragons. If only Bethesda had given him different actions than the rabble.
Bethesda has improved conversations immensely but the people still seem stiff, as their voices can be sometimes dozens of times more enthusiastic than their bodies. Particularly Sheogorath and Cicero, who scream and shout their sentences but never do much more than wave their hands a bit and tilt their head.
I have few complaints with the games performance. There are bugs, many bugs, and some infuriating bugs, too. The game crashes occasionally. It's to be expected with such an enormous world.
Bethesda has some brilliant things in this game and many great things. For that matter, most things are very good. It simply could have used a bit more shine and variety to the quests, particularly the Main Quest.
If you are thinking about buying this game. I highly recommend it. You can't do a whole lot better than Skyrim. Just don't expect everything to be as perfect as you have been told. It has flaws, just like every game does.