Shingeki no Kyojin: Ano Hi Kara

If you've watched the rest of the series then you won't gain anything new from this episode. It's a recap. Now, anyone who complains about it doing its job -- recapping the events of previous episodes -- is missing the point of the recap. It's not a stretch to say (based on the production errors in previous episodes) that the animation studio is struggling a bit to get this show out in good quality week after week. The reused animation and story in this is giving them a week more buffer time to prepare the episodes. This is a good thing as far as ... I can see. If you're just starting the series, feel free to skip this if you want to, you obviously will not miss anything as it is a recap of things already watched.

Recap as recap is nothing special, unless of course you want to refresh your memory before watching season 2

Thank you for the brief retelling of the first part of season 1, to be honest, it is quite possible to watch this movie for the place of the beginning of season 1, but why when there is a full season with all the details. You can describe this movie in 4 words "the same eggs only in profit" Hahaha. If it wasn't a recap, maybe I would have put 8, but it's so patchy... Oh, the soundtrack is fucking great at the end ;)
⠀⠀⠀⣀⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⡠⡄⠀⠀
⢰⠒⠒⢻⣿⣶⡒⠒⠒⠒⠒⠒⠒⠒⠒⠒⡶⠊⣰⣓⡒⡆
⢸⢸⢻⣭⡙⢿⣿⣍⡉⠉⡇⣯⠉⠉⣩⠋⢀⣔⠕⢫⡇⡇
⢸⢸⣈⡻⣿⣶⣽⡸⣿⣦⡇⣧⠠⠊⣸⢶⠋⢁⡤⠧⡧⡇
⢸⢸⠻⣿⣶⣝⠛⣿⣮⢻⠟⣏⣠⠞⠁⣼⡶⠋⢀⣴⡇⡇
⢸⢸⣿⣶⣍⠻⠼⣮⡕⢁⡤⢿⢁⡴⠊⣸⣵⠞⠋⢠⡇⡇
⢸⢘⣛⡻⣿⣧⢳⣿⣧⠎⢀⣾⠋⡠⠞⢱⢇⣠⡴⠟⡇⡇
... ⢸⢸⠹⣿⣷⣎⣉⣻⢁⡔⢁⢿⡏⢀⣤⢾⡟⠁⣀⣎⡇⡇
⢸⢸⠲⣶⣭⡛⠚⢿⢋⡔⢁⣼⠟⢋⣠⣼⠖⠋⢁⠎⡇⡇
⢸⢸⢤⣬⣛⠿⠞⣿⢋⠔⣉⣾⠖⠋⢁⣯⡴⠞⢃⠂⡇⡇
⢸⢸⠀⢙⣻⢿⣧⣾⡵⠚⣉⣯⠶⠛⣹⣧⠤⢮⠁⠀⡇⡇
⠸⣘⠢⣄⠙⠿⢷⡡⠖⣋⣽⠥⠒⣩⣟⣤⣔⣁⡤⠖⣃⠇
⠀⠀⠙⠢⢍⣻⡿⠒⢉⣴⣗⣚⣽⣋⣀⣤⣊⠥⠒⠉⠀⠀
⠀⠀⠀⢀⣔⠥⠒⢮⣙⠾⠀⠷⣚⡭⠞⠉⠛⠦⣀⠀⠀⠀
⠀⠀⠀⠉⠀⠀⠀⠀⠈⠑⠒⠋⠁⠀⠀⠀⠀⠀⠀⠀⠀⠀

Technically, if you're that type of person who watches only a few episodes when you have free time, you might find this episode helpful to refresh your memory.
However, i'm that type of person who finishes any anime that interests me in a few days.

This episode is called a special, although clearly a recap.
I watched this anime, thinking it was an actual special, unknown it was a recap.In my perspective, this 'special' has no merit to me.
Surely, if you bothered watching it, this recap may have refreshed your memory and showed you points you may have missed, but overall i think it's a waste of time.

I ... recommend you do not watch this so-called special, unless you want either of the above.