This includes some vague spoilers for both shows.
I was discussing this with sinbrat
last night. Not parallel's so much in terms of specific characters or storylines, but in quality and the lack thereof.
This is all my opinion, and my reactions to them, naturally.
Both shows had a very strong first season (when so often first seasons have teething problems), with a very high number of rewatchable eps.
Both shows ditched a character that was in the S1 opening credits (Doyle and Mandy).
Both shows had mixed success with S2. WW started very strongly (ITSOTG), but got crappy for a while, before coming good. In Angel's case it was a up and down the whole way through. Both have problems in that they build up storylines well, but don't resolve them well/wrap them up too quickly. Angel is particularly bad at this (see Dar.
Both shows have had a marked downturn in S3. They're still watchable, but there's less substance to them. Rather than being caught up in an ep, I'll be enjoying it for the little things. And episode shouldn't be made enjoyable by Russell Crowe jokes and slashy moments, while the rest of the plot has me going 'what the fuck?' They should be the icing, not the sum total of good stuff.
The actors are still giving their all, but the writing is just not up to scratch on either show.
Both shows have had new female characters (whom most people don't like) thrust into the cast and into uninteresting relationships with a lead male (which is boring most fans). Other relationships, especially slashy ones, have been reduced/virtually eliminated.
Aaron Sorkin is an arrogant asshole. I'm not so sure about Greenwalt and Minear.