I bought this game when launched but I just finished yesterday given that I wasn't familiar playing in Vita this kind of game. The first part took me very years trying few minutes at a time. Several games were released and those took my attention... Well, I gave it a try again and I am happy I did.
1) The story is good, but no essential to the overall assassin´s creed world. It is like an add on... I think this game was developed at that time to promote the vita selling given the good reception assassin creed III had a that time. However, I enjoyed it very much. It is not as length as previous installments, main story with some side quests could last around 12 hours. (Be aware there are fake and true ending, PS spoiler: just have to find Citizen E).
2) Gameplay: It is the same, for me it wasn´t the game to be play on PSVITA, but after getting used to it. It is ok.
3) Graphics: as I finished the game in 2017, the graphics are horrendous, today's mid-rage phones look far better... But this is not game fault. Just to warn you if you haven't tried it yet. There is a HD version for other console and PC.
4) Soundtrack: is good, I couldn't appreciate it the most due to VITA speakers. Should have played with headphone.
My only concerns is about the Vita, we are in 2017 and my Nexus 5X and iphone 6s have far better graphics than the VITA what makes me just beating the games I have only because I purchased them in the past and I don't want to waste my money (despite I paid full price for all the game)... Next games to try: Resistance and Uncharted.... If I have some time to waste... the free games I stored given free by PSN Plus.