Decent, but that's about it.
The main story is quite short and fairly disappointing as it lacks any unexpected and "Wow!" moments, not to mention you can beat it in around 12 hours. Dialogue is decent, but nothing too overly amazing, as you never get too many options that actually make a difference. Don't forget tons of glitches as well, even though I suppose most people expect that from Bethesda games anyways.
While the previous complaints don't ruin the game, here comes the part that does. First, the looting system is absolutely atrocious! Very rarely will you ever find or get anything that you will actually use, as almost all of the best armor is the one you make (smith/enchant yourself), not to mention that chances are (if you plan to play for at least 100 hours) for around 60% of the game you will be using the same armor, as "best in slot" items can be found quite early on and will never get replaced. Personally, one of the reasons I love RPGs is finding that "fat" piece of loot for completing a long quest. Skyrim also has poor level scaling, and as such the game gets more and more ridiculously easy as you progress, to the point were you can play it on the hardest difficulty while doing something else at the same time at around level 40. Completing quests also feels pointless, as for most of them there are next to no rewards (except for money, which you will have tons of and nothing to spend it on). Oh and I almost forgot to mention that there are about, oh, I don't know, 10 very similar dungeon layouts used for around 300 dungeons! After the first 20 hours, I was actually not even sure which places I have explored, and which ones I haven't.
Don't get me wrong, Skyrim is still a fairly decent game that has a fun combat system, tons of customization, and some interesting side quests. But if you are expecting to find an amazing game that you will spend hundreds of hours of pure fun in, this is not it. That said, if you have nothing better to do, this is still a fairly fun game to waste your time with.