As much as I'm not a fan of the present day plotline, what you need to remember is that this isn't black flag. It's AC4: Black flag. I disliked the older ones as well, and it was Black flag that got me on board. Once we move on to the next thing, I probably won't be interested again, but there it is. It's a pirate game, yes, but in the AC universe, therefore you should know to expect it going in.
The feedback after missions? Love the idea. I think more companies should do it, seeing you're not forced into actually taking part and it gives them actual, honest feedback that everyone can contribute to.
While those arbitrary `spotted, start over` fails bother me, the only ones that I can bring to mind are tailings and eavesdropping, which seems reasonable to me.
As far as I've noticed as a person who was never an AC fan before this, actually disliking the olde rones for whatever reason, this IS a pirate game, and a darn good one. Honestly, as much as I dislike it I'm loathe to say 'ditch the present day stuff' because of the potential it has. I know Ubisoft aren't interested in a modern day AC, but not interested dosen't mean never and I'd genuinely like to see where else they take it, seeing the franchise is gonna keep going a while. Maybe I won't like the next one, as I didn't the old. Only time will tell, ey? (Unless someone in the future with an animus can tell me now. In which case, greatly appreciated!)