I am a lazy person by nature, and for that reason, I love Skyrim's leveling system. I play TES to learn the overall story behind it, so actual gameplay and mechanics are just things I have to work through in order to get that story--anything to make that process easier is okay by me. For people who care about that stuff, though, Skyrim is very, very simplified in that way.
As far as that story goes, Skyrim's not bad when taken on its own. Like Oblivion's storyline and backstory, if you put it next to the games that came before it, you'll find quite a few inconsistencies and changes. For me, that makes Skyrim a poor addition to the series, but as long as I'm willing to accept the inconsistencies in the ancient history and metaphysics in order to learn about the very interesting current events that Skyrim reveals, I still have plenty of fun. Skyrim also lacks what Oblivion and Morrowind provide in spades: a detailed history that leads into the current problem (Skyrim gives us a general outline, but very little real information about it). On the other hand, Skyrim provides where Oblivion fails: an interesting present-day setting with at least one faction questline that asks you to make a decision that could affect issues across the continent for years after the scope of the game itself (I'm thinking of the civil war specifically, with its implications to an Empire that's already crumbling and still facing the Thalmor threat on the opposite side of the continent). Morrowind didn't have any comparable faction or side quests, IIRC, but its main quest (and Tribunal DLC) was just as politically-motivated, and just as important in terms of the course of the future (even if you as the player didn't really have a choice in which side you took; thanks a bunch, Azura). Basically, I believe that Morrowind provided both an interesting current setting and an interesting backstory to build it; the following games did half the job, but didn't manage the other half nearly as well. That said, I admit that most of my opinion about Oblivion's current setting is colored by the hints of what it could have been that came in Morrowind and previous games, and thus disappointment that I didn't see those things in the game itself. My opinion about Skyrim's backstory is slightly more objective: Once I realized that I was willing to accept some of Oblivion's lore changes if I found information that made them interesting or plausible enough, I started to look for that kind of information in Skyrim's backstory, and found a whole lot of nothing for my trouble. There's not much information about it at all, which as you might imagine makes for a pretty vague and uninteresting story.
tl;dr: Skyrim's backstory is a blank slate, compared to Morrowind's as well as Oblivion's. But its present-day setting, current events, and other current story tidbits are much better written, and are at least just as good as the setting of Morrowind. And I like Skyrim's gameplay and leveling system better for the most part (though I'm pretty lazy, so that opinion probably doesn't help anyway). Taken on its own, Skyrim is a good game--I would say better than Oblivion in terms of current setting and gameplay--but when placed in the series as a whole, it seems shallow in terms of writing and story, where those questlines that have a good story are poorly written and repetitive, or perhaps more accurately rushed. Skyrim's faction quests also feature a problem present in Oblivion, where the factions don't seem to interact with each other or the world around them--at least in Morrowind we were reminded that these factions existed in the same world when they would interact (if only to try to fight one another), but in the last two games their questlines have been very self-centered in comparison.
As an aside, I can't use the magic system in Skyrim nearly as well as I can for the other two games. Skyrim's spell-charging mechanic ensures that I always mistime my on-target spells. Coincidentally, Skyrim has managed to fix everything I hated about archery, so even though I'd prefer to be an awesome mage, my overall ranged combat effectiveness is better than ever. Figures.