LDiCesare: Letho is a pitiful Nilfgaardian sellout in the end. He didn't have to do what he did. Geralt sides with kings out of necessity. There are quite big differences in character here.
The Letho part of the story is interesting, but the whole story revels too much about politics and not so much about hard moral choices. There are, in fact, almost none of these in TW2. For instance, choosing whether to save Triss or Anais isn't much of a dilemma, even less when you realise Triss will survive no matter what, so saving her is obvioulsy a bad choice in retrospect.
Siding with the Order or the Scoia'tael, or even funnier trying to remain neutral, was much more interesting than the current installment.
Some endings are also very poor at telling whether people still believe you to be the kingslayer or nor, which was kind of all the reason why Geralt got embarked in that quest in the first place.

GrimTuesday: How mad would you be if there was an expansion pack, where you control Letho. I mean, it would technically be The Witcher, right?