I had high hopes for this as the books about the Watch are some of my favourites but that looks bad. It isn't the Vimes I would picture in my head but if they're collating all the Watch stories together, I suppose it could be alcoholic Vimes pre Sybil. Though off the top of my head, I'm struggling to remember the chronology of when Carrot, Angua, Cheri et al join the Watch in relation to Sam meeting Sybil in Guards Guards. I'd agree about why is Vetinari a woman?! It isn't like the whole Discworld series is short of female characters. But sticking to the Watch, the focus will (should?) be on Vimes but surely Angua and Sybil are going to feature strongly.
Still, I'll probably watch the first episode to get a better idea of what it's about as trailers aren't always the best thing to go off of and I don't want to judge a book by it's cover (I'll see myself out).