During the XY campaign there was not many things the fans were upset about. Probably the only one was Mega Evolution and how some people hated the idea and others loved it right from the get go.

With Sun and Moon there's surprisingly few things that divide fans already
>Z Moves. Some people love it, others hate the silly dance poses and think long animations for individual moves is a waste of time (we're unsure if there's the option to turn them off as regular moves). Also its possible some pokemon will become broken like some megas did
>Mega Evo return. Some think it wont, some think its cofirmed it is in SM (Mega Glailie on the ad for 2017, Mega Gradevoir mention in Jangmo-o article, Sina and Dexio have mega rings) but either way both options will upset someone
>Ultra Beasts. Again some think its original and interesting, others hate the idea and designs and think its quite non-pokemon like
>No gyms. Trials might be a good replacement but removing a staple of the series wont satisfy everyone
>Alola forms for Kanto mons. While most people like the idea in general lots of people are upset about making it gen one only

Do you think people will just get over the issues and differences or maybe this is just a taste of how vp will look like around January 2017? I havent listed Pokemon designs because those are always subjective

We still dont know about many crucial parts of the game like: difficulty level, post game content.