What I loved about this episode is this battle between Twilight and Tirek, I didn't expect something like this to happen. Nor did I really get how one minute Twilight can't control the immense magic given to her, and then the next she's in full control, I'm not sure how this happened, which is a plot hole in itself. But then there's this: I just have a problem with the mane and tail lengths, they should look like this: People will have their own opinions, but I respect them if you have one. So what did you think should have been done?
Both styles look ridiculous, but at least the longer manes match the over-the-top aesthetic of the Rainbow Power designs.
Oh yeah, I loved the part in "The Cutie Remark, Part 2" where the Mane 6 used their Rainbow Power. Unless, of course, you're referring to Season 4, Episodes 25 and 26. On topic, though, I'm okay with the long manes, especially since Rainbow Power is seemingly inspired by another fictional Super Mode... just Saiyan.
The designs need the long manes to effectively portray the "power" aspect of Rainbow Power. Notice that Twilight, Dash, and Fluttershy's wings have all changed in size and form as well. All of their manes also flow in some way, like Celestia and Luna's. The normal mane designs are cute, but come across as more of a special makeover rather than the result of powerful, body-altering, centaur-destroying magic.
The title confused me at first, but now I, see what you meant. I think you should fix your title about the rainbow power ponies and not just putting a title from the show.
