After seeing the notification from MAL I was excited for this special episode. But it was a complete summary. Even though it's a summary episode, I watched all of it without skipping. If you have watched the anime week by week, you may have missed some details or did not fully understand some parts, and if you don't want to waste your time watching the whole series again, I recommend you to watch this directly. Shortly 11 episodes in 1 episode. But if you haven't watched the whole series and you're planning to watch this one summary episode you won't be able to understand theseries.

Basically it was a great summary for someone who watched the whole series. I recommend you to watch it before 2nd season.