I was real happy with this episode. Dash has been getting more and more egocentric and, by relation, becoming a bit of an ass. There was no way she was gonna get into the Wonderbolts like that and she may even have started losing friends. I'm a pessimist though, and all is fine now. Why? Instead of Dash being kicked on her flank and told she was a jerk, she got to watch someone with the same drive and ambition fall to the dark side - and it showed her what was important. Dash should be nicer in the near future.
Also, Pinkie tried to cut her in half with that hug.
Also, I was happy to see more dark colored ponies. Sure none as main characters, but I'm glad they're getting more realistically diverse and not all cartoony bright... Although quite frankly it was appropriate seeing as how it's a cartoon.
I was a bit disappointed Dust didn't stay. Go-...sh Darn it. I liked Dust. Don't ask me why. Also, have you noticed that anyone whose friends with Rainbow, and not a background/main character is a jerk?