Well, I finished the Dragonslayer quest chain tonight. That was the last major one I had to finish, so except for a few remaining quests that are out of character for my guy, I'm more or less done. 250 or 260 hours of entertainment, a good value by anyone's measure.
Overall Skyrim is a great game. Regardless of how many valid criticisms can be made of certain aspects of it, as a whole it succeeds on an epic scale. Certainly the number one way in which it succeeds is in its depiction of the physical environment. The scope and quality of the scenery, the ambient effects, the aural background, are all just magnificent. At least 75% of my continued interest in the game came from just wanting to continue exploring, and not wanting to miss anything.
But there are valid criticisms. Major quest lines are too short, some of them ridiculously so. The Thane quests stand out, but the "Guild Leader" quests aren't much better, and even the Civil War feels thin. The most epic quest line for me was definitely the central Dragonslayer quest, and it led through some of the most inventive and inspired scenery in the game.
Dungeons are too linear. I know a lot of people like not having to make decisions, and avoiding the feeling that they might get lost. I'm from the generation that made maps on paper to follow along in games. I like having to figure things out. Virtually every cave, barrow, dwemer ruin, and quest dungeon in the game has a predictable linear path from entry to exit. The forts are a notable exception.
The game is too easy. Dragons are too easy. Even an un-smithed, un-enchanted character build leaves the player way too powerful by level 50 or so. I played an archer and by the end of the Dragonslayer quest he basically walked through 15 or 20 Deathlords without even popping a heal potion. In addition the game literally showers the player with loot and coin, to the extent that it becomes meaningless. I finished with 170,000 gold, all the houses completely kitted out, and all my barrels and chests stuffed with loot. The only kind of loot that didn't seem ridiculously overabundant was good arrows and anything Daedric.
Too many quests are broken if you encounter them out of order. In a sandbox game the quest scripters have to consider different orders of events. It's not that hard a problem to solve, and a number of quests in the game handled it just fine. But a large number didn't, and so you ended up with items in inventory associated with some unknown quest, and unremovable until you Google up the related quest and go solve it. In many cases even that wouldn't help because the quest just wouldn't work when the item was found first.
Enough has been said about the interface. It's beyond terrible. And regardless of the relative merits of the design, on the PC it is just broken, and difficult to use, and frustratingly limited. A serious flaw on an otherwise great product.
The voice acting... what to say here... terrible mix of weird accents, inflections, just a complete hodge-podge, and most of it not very well done at all. I think I prefer reading text to hearing the same voices over and over and over again every time I move through a town or interact with a merchant. At least text can be ignored. Until we have text-to-speech that is good enough that the game can generate voices for characters, my opinion is just forget it. I'd rather have all that money spent on...
Lastly, and definitely not leastly, my number one complaint about Skyrim is that the world is just stupid, unresponsive, unknowing. The NPCs repeat the same scripted lines over and over again. Regardless of what you do, almost nothing changes. They don't know the civil war is over, they don't know I'm a powerful warrior, they don't know I'm Thane of the hold they live in, they don't know I've killed 50 or 60 dragons, most of them don't even know when it's night. I haven't played a stealth/thief character, but I have to imagine it's a bummer to enter a city at 3:00 AM and find the whole population, kids, guards, adults, wandering around the streets with all the torches blazing.
For my part I think the visuals and sounds in Skyrim are good enough. Now I'd like to see Bethesda focus on using some of the prodigious amounts of CPU available to make the NPCs smarter and the world more responsive to my actions.