.... Can I sum it up with "everything" ? Reborn is way better in everything than other games :|
Difficulty - just right. Hell, some gyms were even needlessly nerfed imo.
story- It deals with all kinds of things both dark and light, realistic things that one can encounter in real life. Best of all, the stories are based on real people and their real lives.
field effects- really, why hasn't a mainstream game thought of that yet? Field effects are a seriously cool feature. In my playthroughs, I always fight my battles without dispelling the field or at least without aiming to do so. It's part of the challenge.
The concept of PULSE- is something I find really fascinating and smart. It seems so natural that an evil organization would aim to amplify a pokemon's natural strength, bringing about natural disasters .
Ways of obtaining certain pokemon- not everything is given to you on a silver platter. I like that you have to put effort and use some brains to trigger various events for getting certain pokemon. It also makes your adventure more full of surprises.
I like that FLY is still not in the game. Makes you venture through the world of Reborn on foot, taking in all the locations, instead of being a lazy nob and Flying everywhere. I'd support getting Fly only after the game is over.
TMs- I like that those aren't so easily obtainable either. It makes people use different Pokemon to overcome obstacles instead of simply going for the most overpowered thing they can find and stuffing it with "the perfect TMs"
my list can go on, but I'll stop here, so there you go, thank you Ame and everyone else for making Reborn exist!