Skyrim is Oblivion on steroids, refined and expanded. Issues remain, but they're very easy to see past when you're in.
But the reason Skyrim is the best Elder Scrolls game so far is because they upped the ante on everything. The magic system is fantastic, possibly the best I've ever seen in a game like this with so much flexibility. Every combat choice is viable, none are obviously more powerful than the other, meaning anyone of any playing style can jump right in and not feel at a disadvantage. The combat system isn't perfect, it's a refined version of the same combat system that the game has been using since the very first one but it's by far the best attempt at a combat system like this that Bethesda have pulled off.
The world is beautifully crafted and thanks to the brilliant graphics it looks awe-inspiring to behold. The world feels a lot more desolate than Oblivion but thanks to the soundtrack having a knack of playing the most perfect music at perfect times and wonderfully varied music playing constantly, it just feels like a much more immersive world. The elements of exploration have been improved, every dungeon is distinctive and where they can vary in quality, it feels so much more rewarding than Oblivion when you explore through caves, find treasure and kill Necromancers and the like.
The Dragon shouts are a blast (no pun intended, don't kill me) and add so much to the game in terms of combat and various things that the shouts can do. The main story is quite good but with a lacking ending, but those playing an Elder Scrolls game for the main quest alone should probably just pick up a Fable game instead. The side quests really shine, many of them being very interesting and engrossing but at the same time some get very repetitive when you've been there and done it all before, dissolving into fetch quests and 'enemy in [cave], kill them and take [item]'. But many things compel you to keep doing them, be it the hope you'll find treasure, a new shout, or something all the more surprising. The level-up and skill system has heavily been improved upon thanks to it being streamlined and has a much better sense of forming itself to your character, making it all the more immersive. Where the whole constellation thing is a little gimmicky, it is a nice easy-on-the-eyes way to keep a track of your character.
The faults are easily the game's glitches and friendly AI. You end up groaning whenever you know someone is going to come with you to explore an old ruin because they just get in the way, especially if you like ranged combat. Or they block the way through a thin cavern and you have to wait until they feel like moving so you can progress. Often when following people you get aggravated due to them being radish-head retarded but at least in this game they often give you the option to travel with or separately from quest characters but it still needs work. The glitches really do hold the game back, be it the infuriating interface glitches or sometimes pressing a certain combination renders you unable to use magic (though this only happened once to me). If these are patched up though, the game will get a higher score.
But when all is said and done, it's an Elder Scrolls game, and it's the best one so far. Highly recommended for those who like to avoid linearity and have a love for medieval fantasy, since this is the best of the best when it comes to a high-end interpretation of this kind of game. It makes Oblivion look goofy in comparison, and it makes Morrowind look like a joke. Everything is improved here and it's all the more beautiful for it. Though it's less bright and vivid than Oblivion, it makes it feel like a new game but with the familiarity to make it instantly accessible to just about everyone but particularly fans of the previous games, and none of the subtleties are lost as a consequence for the accessibility so don't fret. Skyrim caters for all gaming styles and much more evenly than the previous games, making it recommendable to just about anyone. Highly recommended, game of the year 2011.