You can pick up the story just fine, and 1+2 aren't remotely close wrt quality.
But it most DEFINITELY had pacing issues around the swamp area.
Witcher 1 was a good game for its time, but unless you consider yourself a serious fan of the universe, I would recommend skipping. It's the only one in which Sapkowski was involved, it has some very good dialogues in random places and it's the only one which gives you a very good feel for what a "normal" Witcher's life is. But the voice acting is only good in Polish, up to the point it's recommended everyone use Polish audio with subtitles if they don't speak the language. And the plot is quite disconnected from the books -> Witcher 2 -> 3 line (I'm really bummed we never got closure on the plot of 1).