I would give it a 9.5, however, because of noticable annoyances I would give it a 8.5. Why?
Yes they made a endless amount of quests and there is a lot of variety in some ways. However here are some of my beefs
1. Glitches, obvious but doesn't effect my rating too much
2. Quantity over quality on quests, they are just too short, main quest is about the right length, but the bosses are too easy.
3. Variety in NPCs is rare, all guards have same armor just recolored, lot of the stormcloak soldiers wear recolored guard armor. Dialogue is not variant, its the same dialogue between all guards and most npcs, just different voices, some with only slight variation in the dialogue(*cough arrow in the knee*). The voice acting is very limited, it seems like there is only 2 voice actors for every type of NPC (as in 2 diff nord ones, 2 elven ones, 2 old guy ones, etc.) Very little variation.
4. Lot is rehashed and re-used.
5. Some stuff turned out very good, just not enough time was spent on them. There is a lot with so much potential that is only touched on.
Yes there is a lot in the game, they did a good job, but they could have easily spent another year on the game to work more on the quests and other aspects. Who cares if they worked on it for a couple already, blizzard tends to work on there games for a half decade before they release a game (And they always get 9.0s or higher), bethesda should learn from them, work on a game until its done, not almost. There is a lot they took short cuts on that were easier since it was a big game.
Overall its a great game and I love it to death, but it still needs plenty of improvement.