This was more of a Twilight episode than a Celestia episode.
I think this episode highlights the problem I've been seeing in newer episodes -- possibly since season 6. Having taken part in Pony Rewatch helped to give me some perspective on things.
I'll give my thoughts on the episode itself after I finish giving my thoughts on this recurring trend I'm alluding to.
From season 6, I've been cringing more and more in certain episodes and I think I understand why: the conflicts in these given episodes come across as very forced. In the really bad ones, not only is the existence of the problem itself forced but also how the situation deteriorates. It's as if the writers are not only trying too hard to make the episodes happen but they're also pushing too hard to hit that rock bottom. This often leads to some very big facepalm moments along the way. Of course, once the pony does hit rock bottom, there's really nothing else to do but hammer it in like forcing a nail through cold steel. If just a little common sense would have been applied at literally any moment along the way, disaster could have been mitigated if not entirely averted.
This episode has all of that. Twilight doesn't think things through. You'd think that a pony who's all about learning would understand that learning anything from scratch takes time and relentless dedication. Learning is more or less making almost every possible mistake before you start to figure out how something is actually done right. Princess Celestia had zero experience and it doesn't look like there was much time to show Princess Celestia the ropes. Worse still, much of the preparation done beforehand had to be adjusted. How did Twilight think she'd schedule all of this in such a short amount of time? Had it been planned a year early, it may have been possible to teach her the basics and allow her to play a simple role befitting of her training up to then.
All that for how this started... As this progressed, red flags were coming up everywhere at every moment. Twilight even made the decision to let her believe that she's doing everything well while she is very clearly making rookie mistakes. I get that Twilight's sole objective here was to give Princess Celestia the star role but at the very least she'd know that she'd need to be earnest with the Princess because that's how she is to fulfill her role as the star actress. The decision to take her to acting class was a sound one but Twilight's insistence on protecting her feelings -- essentially treating a princess with a thousand years of experience
like a foal
-- made it impossible to make any progress whatsoever and it was just agonizing to watch. She finally reaped what she had sown when the set is virtually destroyed, leaving her with nothing else but to vent all the pent-up stress -- and, of course, what stressful rant would be complete without being overheard by the very last pony she wanted to hear it. This just comes across as so avoidable to me and that made it so painful to watch. I don't recall ever having facepalmed and groaned so much watching an episode.
Luckily, though, all the other parts of it were fantastic. Princess Celestia prancing around with impulsive delight was just too adorable. Really loved the first scene before the intro.
Then there's the second half when Twilight had been caught. Princess Celestia was right to be disappointed and angry. After their heartfelt exchange, Princess Celestia was brought back to the set and that's where she put her managerial skills to good use -- and boy, was she killing it! Seeing her fix such a broken situation with such elegance and skill was truly an amazing sight! From salvaging the set to directing Spike and the other ponies in real time to rectify whatever problems popped up... It was simply nothing short of spectacular!
In hindsight, had it not been for Twilight's blunderous shenanigans, we would not have seen Princess Celestia make picking the pieces up look like such an art. Perhaps I can be thankful for Twilight's blunder for setting up the stage for such a performance (pardon the pun).
Then, of course, there are things other than the plot to be thankful for. Princess Celestia has already had episodes where more of her personality has been expressed but this one easily tops the list (and probably will for some time to come). We also got a bit more of Equestrian lore here. Apparently, the unicorns all worked together to raise the sun but despite their combined power, their power was still being depleted. Princess Celestia, on the other hand, could carry out the astronomical task without exhaustion. It certainly is interesting.
Another thing: anyone else remember that Fluttershy dressed up as Princess Celestia before in Testing Testing 1-2-3?