This is just amazing, huge worlds and non-lineraty hold me on!
I was just blown away with the impressive detail put into the game at almost every turn in the world, from the NPCs to all the choices for your character and the variety of weapons, armor and accessories.
Not only the main quest is lengthy (60+ hours myself), but all the side quests with the guilds/factions and other things keep you hanging on for more.
The modding community is pretty much flourishing, with this game which seems to extend the life of the game...I do recommend several mods if you want seemingly original gameplay: "No Psychic guards", "MerchantPlus", "Martigen's Monster Mod" and "Life".
You need a really good computer for this game of you want to squeeze as much detail for this game.
I strongly recommend buying this if you are into RPG games.