I'd say it's pretty original. Bethesda likes to throw in little references to other stuff—for instance, it's possible to discover an item called the Notched Pickaxe, and there's a character named Temba Wide-Arms, which might give you a chuckle if you're familiar with a certain episode of Star Trek: TNG. But, that aside, it's a very rich world with its own mythology, and each race has their own spin on it, which is fun.
The races are fairly unique, too. The three major divisions are Men (humans), Mer (elves), and the Beast-peoples. For humans, you've got the Imperials (Roman-inspired), the Nords (Viking-inspired), the Bretons (English-inspired), and the Redguards (I don't know much about these guys). The elves are fun. You've got your Bosmer (Wood Elves), Dunmer (Dark Elves), and Altmer (High Elves—these guys are real jerks), but then you've also got the Orsimer (Orcs), the Dwemer (the lost race of Dwarves), and the Falmer (deep-dwelling, blind, not nice). The Beast-peoples are the Khajiit (cat-people) and Argonians (lizard-people).
But, returning to the game itself, the basic storyline is this: you are the Dragonborn, a legendary figure the likes of which hasn't been seen in hundreds of years, much like dragons themselves. Also, the dragons are returning to Skyrim. This is not a coincidence. Whether you've appeared because of them, they've appeared because of you, or both, isn't exactly clear. What IS clear is that they're bad news, and you're the only one with a hope of dealing with the problem.
Meanwhile, there's a civil war going on with factions supporting the Imperials on one side and the Stormcloaks on the other. The Empire has recently signed a treaty with the Altmer that outlaws worship of Talos, a figure particularly revered in Skyrim because he was a Nord who ascended to godhood through his great deeds, and many people aren't particularly thrilled with being told who they can and can't worship. It's pretty clear that the Altmer are bad news, but on the other hand, with the threat of dragons looming, now is not a great time for Skyrim to be divided against itself. Nobody's really in the right. You can choose to take a side, but you don't have to.
In fact, you can avoid the main storyline forever if you want to, too. One of the great things about the game is that you're not really forced into anything once you escape the first scenario.
I can't think of any other fantasy it draws on in particular. Skyrim kinda reminds me of Middle-earth, but I think that's only because there's a sense of grandeur and rugged beauty about them both. (And Skyrim really is gorgeous. At night, when the Northern Lights are out... stunning. [It might be useful to know that I'm very picky about games: they have to be nice to look at and listen to for long periods of time, or I just can't be bothered.]) The Nords and the Rohirrim are drawn from the same stock, certainly, but they're definitely distinct. The game also shares certain aspects with other RPGs—get into encounters, fight, loot treasure wherever you can get away with it, gain XP, gain levels and special abilities—but again, it has its own distinct flavor that makes it more than a D&D knockoff. And anyway, I like D&D.
I really enjoy the amount of detail put into it, though. Throughout the world, there are books you can pick up and read that give you information about the history of Tamriel; and some are just amusing little yarns. I spend a lot of time reading in this game. ^_^; And then, the people each have their own little stories. I talk to just about everybody, just to see who they are. You can't engage in dialogue with everyone, but apart from the guards, they almost all have something unique to say. It's the little details like this that drew me in. The main story is interesting, but I like a world I can really sink my teeth into, and this fits the bill. It's absolutely huge. I've explored a fair bit of it by now, and there's still a lot more I haven't seen.
... That's a lot of words, and I'm not sure how many of them actually address your question. Let me know!
~Neshomeh