Them's Seeing Ponies

You're not the only one. I didn't really like it much either, yet I can't entirely put my finger on it why. I found the "Pony of Shadows" underwhelming. He never really came across as a threat with all the Pillars around. He deserved a much more threatening role.

But I guess it's mostly the Pillars themselves. Not only did they come back but then they also stay in present day Equestria. It just ruins the mystery of their legends and stories for me. I don't know, it just ruined it for me. It's not their time and place to be in.

I agree with your point about the Pillars. It's interesting that the writers decided to roll with the idea, but it does ruin some of their mysticism (ands it was also kind of a copout considering how little of a reason the other Pillars had to be in the episode aside from Star Swirl).

To me, the major issue with the episode was that it dumped a ton of exposition onto the audience about the conflict between the Pillars and Stygian/PoS and how major the whole conflict was, but never really showed the audience anything to justify any of this exposition or why exactly PoS was a threat/why the audience should care about it despite the episode telling us we should be caring anyway (which is particularly underwhelming considering that 22 minutes were basically spent building up to is return, only for it to be for almost squat), which led to most of the episode coming off as the cast just wandering around and talking about the threat that the audience never sees nor is given a reason to invest in. The whole experience just felt sort of 'hollow' to me.  

I liked most of it... except for The Pony Of Shadows; he turned out to be pretty lame and suffer from show-don't-tell.