According to Bethesda, it is rare for people to spend less than 80 hours playing Skyrim. I've been playing Skyrim since the day after it came out and I have 350+ hours playing such a great game. It's not really suprising that this is the case as it takes 80 hours just to complete the main story and a few side quests... Then there's wanting to finish everything, making different types of characters and getting all the achievements/trophies.
There's also Skyrim DLC on the horizon to try and further that game time even further. Personally, I would like to see different types of dungeons (rather than just the generic daedric dungeon that's great the first 100 times but gets annoying after that) and more weapons too; different types of arrows would be good and there's even talk to spears! Make it happen, Bethesda.