From the review: "...the most compelling part of The Witcher is that the dialog is what pulls you into the world. The game engine is based on old Neverwinter Nights code, but has been tweaked and improved over the years to deliver not-quite-Oblivion levels of visual detail. The voice acting is passable, but the sheer volume of it means that some is better than others. But it's the actual dialog, the words that match the voice acting, on your screen that will make the difference."
UGO gives The Witcher an overall rating of B+.