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.