My overall opinion is very good, with a reservation, however, on the fact that the chosen axis inevitably leads to a fragmentation of the card; places individually are small and only the sea linking keeps the idea of an open map. But apart from that, I really enjoyed repeated once more, and in a context that allows sending heavy graphically (the slap when we land on Great Inagua in the circus waterfalls! Or at Tulum - that has nothing to do with the real site, for once I could see myself having gone there) the feeling of freedom to drive for hours on various missions.
After AC3 I thought it would be disappointing and not at all. The turquoise waters of the Caribbean are a pleasure for the eyes, we want to paddle of sandbanks islands (which requires us to make the collection of chests and fragments animus). Ancillary activities are varied and well integrated in the game: destroy the strong brings up the map of the seas (with the same points on earth observation), hunting (including the water a great time the first! times) enables the production of character improvement ... The progressions are well managed (catch a humpback whale before a shark would have lessened the pleasure) and articles are also released over the progression of history (after 20 hours we still had not given me the opportunity to have the diving bell for exploring wrecks ...). Multiple improvements for both the boat for the character (held included) guarantee hours scouring the seas to loot needed for their purchase.
Some criticize the plot, and yet I find that once again Ubisoft did an amazing job to create a world and a story that makes sense with a very good script and has reinvented itself.
Finally, with 70 places to discover (marketing argument certainly, some being only the fishing grounds ...), there is enough to do before claiming to have been around the game. If you do not like me move not fast on the main plot for the pleasure of prolonging the game, expect good 50 hours of play. Unfortunately I can not talk about the multiplayer, which have not tested.