For me the devs behind the Witcher have managed to balance the feel of freedom in the game but with a good story and purpose behind it.
And that has always been the holy grail in single player rpgs (like Gothic, Oblivion etc) A game that gives you the freedom but also give you the story and structure.
Like a single party KOTR but with more freedom and intriguing story as well as a entertaining combat.
For me Vampire Masquerade Bloodlines does the RPG luvliness from a dialogue perspective. The dialogue and options depending on your character were phenomenal and second to none really, but its combat suffered but still a great great game. (after patch!)
But from an action and gameplay perspective The Witcher is the top dog in this genre. They've combined the immediacy and addictiveness in the combat of Diablo, the feel of freedom of Gothic and the engaging story of Bloodlines/KOTR/BG (or even Planescape Torment but that might be pushing it but havent finished the game yet so who knows)
And they did all that with much much less bugs than a lot of the aforementioned titles
edit: gonna try playing it on my tv see how it plays