I enjoyed it as a lark just fine, even despite the silly golden arrow ending; Gatiss noted it was "probably the most frivolous of the season" or something, and out of the first three, he appears to be right.
But what it highlighted for me was how great the direction and cinematography of the first two eps were! They were both directed by Ben Wheatley, someone I know next to nothing about, but -man!- Those two eps played like strange dreams and really had a different feel, which I think was a good call for making the new era feel new and different.
Now we seem to have reverted to the usual style of "television directing": "Ok, let me check here... everyone's in focus, yes... the Macguffin in his hand is in shot, yup..., ok, all good - cut!" It all works fine enough and gets the story across, but without any noticable no flair or atmosphere, you know? It takes no risks, just toddling along paying off its usual slim rewards...