My problems with the Matt Smith era aren't really to do with individual episodes being bad; they're bigger issues that tend to negatively affect every single episode. The writing and characterisation are the most glaring problems.
I think the dialogue is forced and awkward (I'm talking about all the ridiculously irritating in-jokes, banter and ~super quirky witty cutesy phrases~) and that's consistent in every single episode. It's so prevalent that it damages my perceptions of the characters. I could never bring myself to care about Rory and Amy because their dialogue was so cartoonish and convoluted that it made them seem less 'real' compared to more believable companions like Rose and Martha. River is the most extreme example of this; she's like a walking, talking, cliched phrasebook. It's SO irritating to watch. I know Doctor Who is fantastical as a concept but it definitely doesn't mean that the characters' personalities have to be, and the show suffers massively as a result, in my opinion.
I also really dislike the way in which Moffat writes women, which tends to be a very common complaint that reviewers etc have about this era of the show. I was hoping he would change his predictable writing up a bit and make Clara less of a quirky, excitable, flirtsy, mysterious Doctor groupie, but she seems exactly like Amy so far in that respect, which is really disappointing. Female companions do not have to be that way. People loved Donna so much precisely because she wasn't, IMO. I know River isn't a companion, but she's written terribly, and is easily the most irritating character I've ever seen on a TV show.
So yeah, if my issues were more to do with plot, I'd probably carry on watching, because it's always been the case that some Doctor Who storylines/monsters/etc are weaker than others. I think the plots have definitely been weaker of late, but it's the general tone that's my biggest issue, and because it's so present in every single episode, I don't like the show any more. I've given it so many chances, but I simply don't like it. I feel pretty sad and frustrated about it because I used to love it, but it's obvious that Moffat won't change his direction any time soon, so never mind!
Thanks for your post
you raised some interesting points.