this One piece TV special was intresting because it gave us a view of what has lead to whats happening now but in a point of view different from Luffy's, hence "Episode of Sabo". It is basically the Dress Rosa arc but in sabo's prespective. we see alot of unseen stuff like how sabo entred the colosuem and how he found out that Lucy was Luffy. quite intersting.
However the story is not really that different, like i said before this is just dressrosa arc in sabo's prespective.The animation was slightly worse than the tv series, for example when Ace is free and he, luffy and mr 3 were in his fire tunnel it looked AMAZING howeve on here it looked kinda sloppy.
This was pretty much a repeat of the dressrosa arc concerning the colosseum part but cut down quite a bit because it gives us Sabo's side when he recognized who 'Lucy' truly was. I like how it gives us more perspective about Sabo's guilt and feelings about how he got separated from them and was not there to try to help but Luffy would just be happy that he was still around and understand that he would have tried to help if he had known.