This post contains spoilers for Bastion and Maldraxxus.
I didn't like Bastion all that much. You'd think I would like it, it being the obvious paladin covenant. But really, they came across as more cult-like than anything, with the whole erasure of memories bit and everyone being transformed into a blue human.
There's also a curiously chill and low-energy vibe, which is odd. I actually liked the bad guys a lot more, except that they sided with the obviously evil big bad.
It's really annoying that all the paladin theorycrafters say that the Kyrian Covenant is far and away the best covenant, especially for Holy Paladins. I don't really want to join that Covenant.
Maldraxxus was more interesting. I liked the different Houses, especially the House of Plagues. Lady Vashj showing up as a major player was quite fun.
The only problem was that ending was quite disjointed. I think one of my addons may have forced-canceled an important cutscene, because suddenly people were talking about being betrayed as if everyone knew it had happened. I disabled all my addons after Maldraxxus just to be safe.
The side-quest with the library was also quite fun. I missed a book on the very bottom floor, and had to go all the way back down and up, evading all the traps again.