So what is different in Pokemon X/Y from Previous ones?

[Exius Xavarus]

1. Graphical upgrades, both overworld and battle
2. New 'Mons
3. Pokemon Amie
4. Super Training
5. Fairy Type(strong to Dark/Dragon/Fight, weak to Poison/Steel)
6. Pokerus is garbage no longer worth the time it takes to find(personal opinion)
7. Infinitely more character interaction than previous games
8. Often meet gym leaders before you fight them
9. EXP Share is a Key Item you can toggle on/off that affects the entire team
10. Capturing 'Mons still results in EXP gain, as if you'd fainted it
11. Roller Skates
12. Move in 8 directions with D-Pad, any specific angle you want, with O-Pad.
13. Trainer Customization
14. Pokemon forms
15. Mega Evolution

And if you intend to pit legendaries against each other, don't send Yveltal out against Xerneas. Evenly matched, Xerneas will repeatedly beat Yeveltal in the nuts.

 

[Someone Depressing]

It's easier. Random battles have been notched down a little. The bosses won't take you by complete storm if you charge into the gym when you first get into town - and you will - but they'll give you a chance.

Honestly, not much. The Pokemon look dumber, the plot is still stuck in the juvenile pits of nothingness, full of idiotic morals and horrible life advice (leave home, trap animals in tennis balls, spend 3 years in mountain before some other kid beats yours animals up, jump off of proceeding cliff) and it's still oddly fun and I hate myself for saying that.

Yeah, still Pokemon.

 

[TheEvilCheese]

6. Pokerus is garbage no longer worth the time it takes to find

If you plan to EV more than a single competitive team Pokerus is a must. Combined with sweet scent which forces horde battles and the 'power' hold items you can max EVs in 5-10 minutes. Much nicer than the 45 mins + it takes to super train. You can also EV 5 'mon at a time like this for insane efficiency.

The main change this gen is making competitive infinitely more accessible.

 

[Mutie]

Well, I've played about fourteen hours so far -

The pacing for leveling is much faster, but the pacing for progression appears to be a bit slower. As stated, I'm fourteen hours in and I've just obtained the third of eight Gym badges, with most of my party being in the low-to-mid 30's. This is because you get the EXP. Share pretty early on and it acts similarly to how it did in Gen. I by giving the entire party experience instead of being equipped to a single Pokemon, though you can turn it on and off at will. In addition, you gain experience even after capturing Pokemon. Also, I might just be slow, because I've spent a fair amount of time exploring and just running through the grass training a bit and looking for Pokemon to capture.

There's a massive variety of Pokemon to capture. There's been Pokemon spilling out my ears here, I even caught a Bagon pretty early on, the earliest I've ever seen a pseudo-legendary in the wild. Additionally, while it's certainly mostly down to personal preference, the Gen VI designs I've seen so far have been vastly better than anything out of Gen 'Gurdurr' V. Litleo is one of the most adorable things I've seen in a long time, and while the starter evolutions are a bit lackluster, things like Talonflame, Meowstic, Tyrantrum, and Aurorus look pretty damn awesome.

It adds (I believe, at least) hordes of wild Pokemon, in which you're going five-on-one with lower leveled Pokeymanz and can't capture until there's only one left. Also Fairy types, roller skates for fully analog movement with the 3DS control stick, four items bindable to the usual "Register a Key Item for quick use!" button instead of the normal one item, and little things like Pokemon-Amie for playing with your 'mons or "Super Training" which I believe lets you boost their EVs or... something. I'll have to look that up. But they're little minigames almost reminiscent of something that might have been in Pokemon Stadium or something, and a cute little distraction for those of us who aren't competitively-minded.

Far as I can tell there really isn't anything drastically different from a gameplay perspective, but this is Pokemon. For what it's worth, I loathed Black with all of my being and am heartily enjoying Y, just because the move to 3D from sprites and the massive roster of old and new Pokemon alike gives it that new shine I felt the franchise kinda needed.

You, my friend, hit the nail directly on the head.

 

[Exius Xavarus]

6. Pokerus is garbage no longer worth the time it takes to find

If you plan to EV more than a single competitive team Pokerus is a must. Combined with sweet scent which forces horde battles and the 'power' hold items you can max EVs in 5-10 minutes. Much nicer than the 45 mins + it takes to super train. You can also EV 5 'mon at a time like this for insane efficiency.

The main change this gen is making competitive infinitely more accessible.

And only those who want their teams right then and there, are going to want it. My personal experience is that all my 'Mons had super balanced EVs when I finished with them and I didn't like that. It could be because I didn't find specific 'mons to fight or don't have specific power items, but I don't find Pokerus worth it at all. I'd like it better if it affected Super Training gains, but alas no luck.

Of course, this is my personal opinion and shouldn't be taken as anything else. I'll edit that into my original response so I don't make people think that I think I'm being objective about it.

 

[Puck]

6. Pokerus is garbage no longer worth the time it takes to find

If you plan to EV more than a single competitive team Pokerus is a must. Combined with sweet scent which forces horde battles and the 'power' hold items you can max EVs in 5-10 minutes. Much nicer than the 45 mins + it takes to super train. You can also EV 5 'mon at a time like this for insane efficiency.

The main change this gen is making competitive infinitely more accessible.

I used the method you describe to EV a Torchic yesterday, but without Pokerus (since my strain is trapped on my Gen V games until Pokemon Bank is released) and believe me, it's still insanely fast. Having to defeat 10 hordes for each stat instead of 5 takes a little longer but only by a few minutes, so I'd hardly say Pokerus is a 'must'. It's nice to have though.

 

[FPLOON]

Can you finally have multiple saves?

No, but man I would kill for that feature.

I'm pretty sure anyone would kill for that simple, yet "always elusive" feature... It would actually make me want to replay Gen 5's story from the beginning for sure... without the repercussions of losing everything I currently had beforehand...

 

[Haefulz]

So many people mentioning Super training as a fast way to EV train. It is not. It's fun the first few times, but after EVing a couple of competitive teams it's a slog. The fastest way to EV train is horde battles, you can (with proper planning) train around 5-10 times faster than super training, the EXP share and Pokerus, combined with power items mean you can EV 5 pokemon that need the same stats as a group very efficiently. Even EVing one at a time it's significantly faster than Super Training.

If you're looking for Pokérus, just ask in a trading thread. All serious competitive players and breeders have it going spare and many will give it away just to spread the love. If you're looking for a trade and can't find one, the best place is probably 4chan/vp (As much as I hate most of the people on there, it's the most actively trading board).

So yeah, OT: As others have said, the visual changes are staggering and the gameplay has shifted slightly. Don't be fooled though, it's still the same core game. Just polished to a mirror shine. I would recommend it wholeheartedly but as always YMMV.

Don't get me wrong, EV training with hordes is without a doubt faster by many degrees, and that's what I'm using to EV train my teams, but the Super Training is much more simple to understand in my opinion, at least to someone who is completely new to the competitive scene. Putting it in the form of a mini game is a nice way to appeal to people who in the past would never have thought about EV training.

 

[Exius Xavarus]

Putting it in the form of a mini game is a nice way to appeal to people who in the past would never have thought about EV training.

It also makes it obvious that EVs exist. Back as a kid playing all the previous games, I didn't even know IVs and EVs existed(I didn't play Gens 4-5). With a visual indicator, it also makes people want to get the best stats they can.