This game is truly what "role-playing" is all about, as you are free to do pretty much anything you want in the entire gaming world.
You are not forced along the main plot, instead things progress as you see fit. In fact, you are probably best off not starting the main plot until you have spent several hours exploring and levelling up your character.
You can travel anywhere, talk to, steal from, or kill any character you want(except vital characters that will stop the main story line from progressing - but it will warn you to reload if that happens).
This is the first game that truly made you feel like your character was alive and living in a real world.
The graphics and sound are jaw-dropping. I'll never forget the first time i was walking in a thunderstorm and a clash of thunder just about gave me a hearattack!
The only mar on this game is the difficulty level. Once your character becomes powerful he is almost invincable. Near the end of the game i could walk into a dungeon and wipe the place out without even casting a healing spell or using a potion.
BUT - this can easily be fixed by going into the extremely powerful editor and changing a few modifiers.
That is the ongoing beatuy of this game - with all the user created mods out there (and some very good ones at that) this game will live on your hard drive for a very, very long time.