Morrowind + Fallout 3 + Oblivion = Skyrim
It's similar to morrowind, in that the game doesn't hold your hand through each phase of a quest. There's a map marker, but nothing is obvious. I loved that morrowind made you figure things out on your own, and skyrim does a LOT of that. Adding zelda-esque puzzles to dungeons was GENIUS. It forces you to read notes you find, examine loot, pay attention to your surroundings, and the like.
It's like Fallout 3 in the ways you affect your reputation with factions. Similarities in gameplay there as well. The Fatalities are fantastic. They happen maybe 5% of the time, but it's the perfect amount. You can also cook and craft things like in New Vegas, but it has more of a WoW feel when you sit there and craft 10 leather tunics.. not a bad thing though.
It's most parallel to Oblivion though. If you liked Oblivion but thought it felt repetitive, or some of the quests were lame, they fixed that. In a BIG way.
Leveling is changed quite a bit too. You still gain skill by doing, and x amount of skill ups lead to a level up. The difference to Oblivion is that you don't need to set 7 attributes and carefully plan your skill ups to maximize your toon. Each skill has it's own WoW type tree and you put one point in per level. Each tree characteristic feels significant however. i.e. level 2, you can put point in 1handed, and your damage goes up by 20%. Or armor up 20%. you get the idea.
I've only downed one dragon so far, and cleared maybe 5 dungeons, and i've easily logged 15 hours so far. I would guess i've done 10 big quests, 10 misc quests, and visited about 1/5 of the world map. If you're concerned about seeing the end of the game too quickly, don't be. There's so much to do, and ALL of it is a blast. (no more speechcraft pinwheel garbage!)
if it's not GOTY, i'll throw my ps3 off the roof.