Huge changes to the pokemon formula since Pokemon X & Y, no longer as it's strictly battle and collecting focused (although still present) as they added variety of mechanics to switch things up a bit and to bring more variety in gameplay. Changes include:

1. No HMs
No longer do you have to carry around a HM slave (s). This has bothered me in the past games as I have to restrict 1 or 2 slots out of my party of 6 to help traverse certain areas of the world. In the place of HMs there are Poké Rides where you can ride pokemon interacting with them on the world map, some you may not be able to access until you've completed mission within the game.

2. Is it super effective?
No longer do you have to look up guides online (unless it's your first encounter) to tell if a move is super effective or not very effective against the pokemon you're up against. After you battle a pokemon once, the game will tell you what moves is super effective or not in the battle menu once you encounter the same pokemon the second time.

3. No Traditional Gyms
No longer do you have to battle your way through gym after gym to prove you're the best out of brute force.
There are 4 islands in the game, each of which are controlled by 4 Island Kahunas
To get to them you have to get pass Trail Captains and Todum Pokemon
Trail captain will give you quizzes, side quests to complete, and/or fight in traditional battles
Todum Pokemon. Basically typical pokemon you find the wild, but significantly stronger and have grunts that help them battle.

4. Rotom Pokédex
Typical pokedex, but with a face and personality attached to it.

5. Alola Forms
Basically different forms of pokemon you seen in previous generations. Either it's there physical form that is different and/or the pokemon's typing

6. Z-Moves
With a Z-Ring and a Z-Crystal you can use a pokemon's ultimate move once per battle. It's not like Mega Evolutions where it stays constant

7. QR Scanner.
You can now scan QR codes to get event pokemon

8. Battle Royal
A 4 player free-for-all where the battle ends after all of one's pokemon trainer's faints. They tally the win-losses of each trainer and the one with best stats at the end wins

9. Hyper Training.
Once a pokemon reaches level 100, they can go through hyper training which can improve a Pokemon's IV

10. Poké Pelago
Your PC Box now has functionality to it. It's like a day care sort of thing, instead of just depositing your pokemon, you can passively train them in the PC or have them search for items

11. Festival Plaza.
An online mode where you can battle other trainers and trade with them. You get festial coins for each interaction which you can spend on clothes, shop or upgrade your pokemon's stats. There's also missions you can undertake to get more coins.

12. Night and Day phase, New Pokemon
Pokemon Sun goes the traditional time route while Moon does the opposite. In Pokemon Moon if you're playing in the daytime, the game will consider it night time in-game. Some events also play out differently like different Totum Pokemon on the same island/trail
In traditional Pokemon fashion you can only get some pokemon in each version so trading is required either with a friend or if you own both versions. Also some pokemon evolve differently in each version now.
I'd say some of overall models of new pokemon are better looking than the last batch in previous iterations of the pokemon series.

13. Auto Run
Your run is as fast as a bike now, and it has unlimited use. You can now move in all directions instead of the traditional 4 and it feels very fluid

14. No Rod
Fishing is now dedicated to specific regions in the world. You cannot fish wherever you want anymore.

15. Photo Taking
You can now take Photos of pokemon in the wild.

16. Team Skull and Aether Foundation
Team Skull is the new antagonist group like Team Rocket, but they have a new style to them as they try act gangster-ish with their animated hand gesters/movements. They have more personality and have a darker tone to their backstory and mission.
Aether Foundation is the opposite of Team Skull as their mission is to cure injured and hurt pokemon. The group is also conducting research on the Ultra Beast (Pokemon) which is a good mystery story in and of itself.

17. Graphical Upgrade
Game looks better than the last, although there are some pixelation around the edges still. Models look more realistic than before, and the battle animations are more visually impressive. There are some framerate issues on 2v2 battles for some reason, but then again I own the launch 3DS. You may not have the issue if you own the New 3DS? It's a turn-based system so it doesn't really matter much in terms of gameplay, but the slow down is noticeable

18. Pokemon Refresh
Similar to Pokemon amie but with more grooming options

-Returning mechanics:
Pokebank return, you can now transfer all your pokemon to Sun and Moon
Clothing Options: Although more options are available, it still feel very limited.
Mega Evolutions return, but none for new pokemon from what i've discovered

Overall, love the changes to the traditional formula as it gives the Pokemon Series a nice refresh and is more streamline to play.

This is a fun game that my six year old grandson can mostly understand and play on his own, keeping in mind that he is somewhat of a gamer already. The only frustration was he accidentally picked his take-along Pokemon wrong and we couldn't figure out how to deselect it and choose another. I couldn't even find the info on Google. He wasn't happy about that, but I think I've convinced him to just go ahead and keep playing the game anyway. The game itself is interesting. Most of the time the characters speak the words at the bottom, but I think it might help to have a stronger reader.

I started playing Pokemon when I first picked up Red and Blue as a kid. I played every game, but Black(2) and White(2), and I have to say, that Sun and Moon are by far the best in the series to me.

People complain about the hand-holding in this generation but truthfully, as a long-time fan, I love it. I love the fact that the attack menus during battles show me exactly what attacks are effective without having to memorize all the type matchups. I love that I can see just how deduffed my Pokemon are, and from what, during battle. I love my Rotom-Dex telling me where to go, rather than putting the game down for a couple weeks then getting completely lost when I come back. The lack of gyms is fantastic; having trials throughout the journey feels incredibly natural. They're part of the flow as you travel across Alola. The story is actually interesting and involved, rather than an afterthought like in most of the previous games. Some of the Alolan Pokemon may seem odd at first, but they all have a certain charm that reels you in.

Poke Pelago's islands are an interesting way to get money, evolution items, and beans to feed your Pokemon. The Festival Plaza is fun because it's not just a trading hub, but minigames as well. Trainer customization is at an all-time high... I can go on and on about everything I love about this generation.

The gist is, I feel like Sun and Moon are fantastic for both new players and old fans alike. You can play just to complete the story, or you can Wondertrade/battle online. You can head to the Battle Tree, or breed Pokemon and shiny hunt. If you're new to the series, this is where to start. Sun and Moon will get you up to speed on everything you need to know, so you can go back to the older generations and be a pro trainer. If you're an longtime player, these games get rid of a lot of headache that the previous ones had. Quality of life is much, much better.

Not too much water eh IGN?

Basically GameFreak took all of our hopes and dreams for Pokemon and put them into this game. It is the biggest leap in terms of quality between any generation of Pokemon. We've gone to a more 3D view point with moving camera angles. We got rid of the gyms and put in trials instead (Thank goodness!), and we have a wonderful new setting. The new Pokemon are a lot of fun, plus we have all the familiar faces as well.

The menus have been improved and streamlined - which is a HUGE plus. One could consider it a minor improvement yet it makes the usability and functionality so much easier, especially in battle.

Also, having the weakness indicators when battling familiar Pokemon is fun too. Though I would have liked if this didn't come up until you captured the type you are fighting. In other words, not showing how your moves affect the opponent unless you have previous captured one of the same and entered it fully into the Pokedex. But small nitpick there.

It's truly as near perfect as a Pokemon game can be and is what I consider one of the best games of 2016. I actually enjoy this more than FF15.