It's basically showing Rainbow Dash being a jerk to her friends, which is a bit OOC. If I had to be honest, I wasn't a fan of RD since the beginning, and this made my opinions of her worsen even if it isn't "her fault."
Also, the prank with everypony in town involved? That was more of a dick move compared to what Rainbow Dash. Seriously, she was scared as hell, and she didn't know that was, supposedly, a harmless prank.