Sonia Saraiya of A.V. Club has watched the premiere two-parter and published a review of the episodes. Her review gives the impression that she has watched a number of other Friendship is Magic episodes in preparation but is not as deeply involved with he show as a fan would be, which gives her an objective outside view of “Princess Twilight Sparkle” (which she still calls “Princess Twilight” in the text).
The review is segmented into a long introductory part that gives the wider audience of A.V. Club a taste of the meaning the show has had for TV animation throughout the past three years before the last three paragraphs critique the premiere episodes themselves.
Being devoted to the unaired episodes, these last three paragraphs contain some material that you may consider a spoiler.
Another review has been published by Kryptonlogic of Everfree News. This review is considerably longer. They dedicate a long section to the synopsis and then add more impressions on the animation quality, continuity, references, inconsistencies, and Twilight’s symbol of power. And it’s gone again.