I can't help but feel like this episode was a meta-commentary on modern anime: "Magical girls now trump giant mechas!"
But on a purely superficial level, this was a very cool and fun episode... and it having both Transformers (that's the first thing it made me think of too) and magical girls is definitely a big reason why.
The action scenes were a blast, and fun to watch. Like Kaioshin, I never really had a sense that KYH's back was truly against the ropes, but on the other hand there
were times when I was wondering just how the heck they were going to beat that big, giant fire-breathing monster. That defeat involving a total Deus ex Machina was slightly disappointing at a literary level, I guess you could say, but I honestly thought it was Ok for an amusing little side-adventure that's mainly there to develop KYH and some supporting cast characters, as well as reveal a shady organization that needs to be dealt with it.
It also was a nice break from the Noumi arc, really. But I'm also glad we're finally going to get to find out what's going on with Chiyu next episode...