Wow, just wow! This is my first elder scrolls game, and it's amazing! Gorgeous landscapes and excellent effects. And there's so much to do! Seems like every NPC has a quest or two.
There's a main storyline, some big sidequest arcs and lots of smaller quests and dungeons. Haven't finished it yet, but I've already played over 50 hours enjoying every minute of it.
What keeps it from getting a perfect score is the horrible 'console' interface. It's hard to see what you have equipped and it's hard to equip the right spells/abilities you want. There are some quick buttons, but you can never know what hand will be equipped with what when you use them. Still a very good game, and hopefully someone will fix up a nice inventory mod soon.