I found this to be a rather amusing episode. Those yaks sure were quite an interesting group. "If things not perfect for yaks, yaks get very angry," and when yaks get angry, yaks smash! Everypony's attempts to appease the yaks... don't go perfectly, leaving Pinkie Pie's party the last hope left. She thought she could find the answer at the yaks' homeland, but it wasn't until she (uncontrollably) came back to Ponyville that she finally figured out that to please the yaks was not to try to make things like the yaks' homeland but to show what the ponies' homeland is like. I also liked how Pinkie's friends discovered that she has a "party cave" with files on just about every pony she knows.
On a personal note, before season 5 had even started, I had thought of some possible ideas of what could work as actual episodes, and today's new episode turned out to be remarkably similar to one of them (foreigner comes to Ponyville, Twilight and friends try to replicate foreigner's native culture, foreigner not happy with results, Twilight and friends eventually decide to instead share Equestria culture with foreigner, foreigner finally pleased). Obviously, many of the details were different, but still, I find it quite remarkable that I was able to roughly predict one of these episodes.
