Assassins Creed Unity is one of the most underrated AC-Games. The climbing has quite a lot of flaws in it, but in my playthrough, they were not too bad, so that they didnt ruin my experience. The story is similar to the predecessors, but works fine, and also brings back some interesting relationship to the templars. The open world of Paris during the revolution is one of the best I´ve ever seen. The streets truly are alive, the threat of the fanatics is always present, and you can really feel the atmosphere of the late 18th century Paris. The protagonist is charming and constantly reminded of our dear Ezio. The modern day story was barely present, which wasnt a bad thing though. And I really recommend you doing some of the awesome Coop-Missions!
To put in a nutshell, AC Unity is a good game, with climbing and bugs as its major problems. Have fun you all! Everything is permitted :)