Just beaten this bad boy, thoughts below:
+Good graphics in the outdoor sections, bit of an improvement on earlier games in the series
+Homestead missions are good fun, fairly simple but varied and give a bit of a 'feel good factor'
+Vibrant cities with lots of citizens
+Not a massive fan of the ship sections BUT they did push the envelope a bit and give the game some variety, the captain of the Akila is a good character also
+Decent game length something like 20hrs
+Frontier bits are good in terms of getting you out and about a bit, the tree swinging bits are a nice touch in terms of retaining the game mechanic and the level design is pretty good in terms of not having too many unclimbable cliff faces etc
-Very cpu limited (single core maxed out), I think you need a 6ghz i7 at the bare minimum to get this running smoothly on a 120hz monitor
-A few glitches e.g. I fell out the bottom of the level once :/ Also a lot of texture popup and people randomly disappearing
-Setting isn't as good as Renaissance Italy
-Still not really enjoying the Desmond sections, find myself itching to get back into the action
-Connor isn't as good a character as Ezio/Altair
-Didn't really 'get' the main plotline i.e. visions, power sources and all that nonsense
-Really clunky console style UI, switching from gun to horse whistle shouldn't be such a hardship, there should just be a key binding for it
Overall my initial view on this game wasn't great and I had it down as the worst in the series since Director's Cut. However it started to improve a few sequences in and I'd say it is perhaps better than Revelations.
Also not really a positive or negative, but I hardly did any hunting or trading at all, it seemed unnecessary.