I personally really hated the teenage dragons. Then again, they were probably written so that I would hate them.
Overall, another solid episode, in my opinion. Decent plot, some touching parts, good music and good humor. Concerning all the Rainbow Dash drama: she'a always been kinda like that, as far as I can remember. She's brash and confident, sometimes to a fault. So while she probably did take it too far when teasing Spike about the apron, her true feelings came to light when she didn't want Spike to leave. I'd say Rainbow was genuinely concerned for Spike's well-being, illustrating nicely her Element of Harmony of Loyalty, in that she is outright devoted to the well-being of her friends, no matter what the stakes.
So with that, I was okay with Rainbow Dash's characterization in the episode. Parts of it did paint her in a negative light, but people have flaws - Rainbow Dash is no exception.
On another note: I have noticed quite a few places (here, Equestria Daily, Ponychan) where people have said they didn't like the episode, though their main reason seems to be none other than the writer - Merriwether Williams. I know Mysterious Mare Do Well was a weaker episode (and in my opinion the weakest,) but that doesn't automatically mean all her episodes are. I've actually enjoyed all of her other episodes (HWE, PYHD and DQ.) None of these I'd say are amongst the best of the series, but I'd still say they are quite good.