Just cut and paste my thoughts on the finale.

That finale was really, really good. Why didn't we get this for the movie instead?
That's the big ensemble episode I've wanted for a long time. Nice villain, nice set up and everyone has some nice moments. The legends come together really nicely and make for a grand finale that has some good flashy action bits, and still sticks to the friendship is magic core.
First episode was a good set up and I really enjoyed the montage of everyone gathering the old artifacts. Especially Rainbow Dash and Spike's part.

I don't even care that Celestia and Luna weren't in it much, at least they weren't captured. I'll happily take "they're just not around" any day. Yeah, they probably should have been included at the end given how big a role the Elements play and them being former element bearers, but with only 44 minutes to work with, this episode was packed already.
It does totally retcon and disregard the Journal of the two sisters though.
Was still a really, really fun story. Even worst-horse gets to shine in it.

This was so much better than the movie. Far more creative, and I wish we had gotten more time to know all the legend ponies, but now that they're back, I imagine they'll pop up again.