The games are very good IMO, I think Ruby/Sapphire were the best (I enjoyed them the most for numerous reasons). Lots of people say lack of (interesting or whatever) post-game content is an issue, I half agree with that, if there were another 1 or 2 towns/cities to visit after beating the Champion (other than Kiloude City) I feel the game would have been better. The positive new features in this game get overlooked (by me too, but I feel other people just take it for granted) the customization is nice (can be improved on drastically though, I don't want glasses or a feather on my hat, I don't even want to wear hat :( ), breeding feels possible to do now with the mechanics changes, megas really changed the game in a good way 90% of the time. I have played the game with Exp-share on and off, I can see why they put it in but it makes the game far too easy on, its not really challenging with it off either though, there needs to be a difficulty level setting to make the AI not stupid, maybe higher leveled pokes and more pokemon per trainer (I'm not sure how much more challenging it would become, too difficult to know in theory alone). Like mentioned above this, the online so much better, its the first time I have actually been able to use an actual game(as in a physical game not PS/PO) to play online.
The post game was good IMO, I think getting the mega-stones was good, kilode City (and everything that is in it), the Looker missions (these are actually took me a long time, over 2 hours), Mewtwo + Zygarde + Bird. I kind of wish I never looked up the mega stone locations, finding them for myself would have been satisfying but the 8PM-9PM thing makes it ridiculous to try it without the internet IMO.
Overall good games, but far too easy (not that pokemon games are ever difficult but these really are too easy). They made Knock Off ridiculous, they need to remove the 1.5 times damage to make it not as OP as it is, critical hits are not as game changing as they were but of course they still can be. Defog being a method of removing hazards has been a good mechanic change too IMO.
Also I don't really know what Amie/Super Training actually do I have messed with them both before it isn't clear what their actual effects are to me (as in the game doesn't make it clear what you are doing, that might just be me)