Incredibly good, high-quality entertainment, Wendy.
Well, yeah, for you. And, of course, you're entitled to think that way.
For me, though, it fell short on both satisfying entertainment and a DW episode. The former because I actually liked the guest characters so much that I wanted to see more of them and how they dealt with what life threw at them. The latter because, with so few DW episodes in a season, the character arc is important, dammit!
So, for
me, while the episode had a lot of potential, it fell short of achieving it, and this is why it felt like filler.
Wendy