After leveling from 70-80 I'm just going to say Questing in WotLK Beta is allot easier than in tBC. Blizzard has done allot to really add more fun to Quests and change up many of the quests and how they are done and try to introduce more fun elements to some quests when possible in the various zones. So questing is much easier overall.
You will still see get X amount of Y in quest design as that can be hard to get around not having some quests designed like that. But as you go along you see Blizzard does introduce some mix of quest type or what you actually do on quests to add variance to player enjoyment of quests. Some Quests involve the lore of Northrend and Arthas as well. As usual some quests are more fun than others and some longer than others as well. Many quests also give allot of XP also, some much more depending on the particular quest type.
But unlike running around any BC zone trying to get X amount of Y for quite a while in Beta its quite noticeable that it doesn't take long to get X of any items I've found. Most of time I've killed the mob and the item drops and drops quickly. That was a very noticeable change in Beta. Some mobs dropped the items I've found close to 100% the time, but not always though much greater than 50% the time though it seem. I'm not sure if that was also due to it being Beta as well. But if it doesn't change much from Beta to live things will be much easier and much faster.
With many quests in the later zone having Phasing and lore elements to them even many of those are not very long or very hard usually. What Blizzard has done with some quests is the ability to stack more quests with Phasing of area or zone into the same area with a different reality to the individual player. Often along the path of some chain quests as the zone change as you go further along some quests.
One the biggest change is Quests that unlock Flight Paths as many quests seem to do that to some areas and usually with a Phasing of the area you were in before. But overall quests are much much easier, shorter and overall fun to do. As everyone have a different level of quest enjoyment, its all up to the player just what they enjoy.