I wouldn't say they "changed" the game but many of the changes are welcomed. I will most likely not pick this one up, Pokemon has run its course for me and the game is not very compelling anymore. I bought pokemon X and only made it past the fourth gym before I lost interest and then I got omega ruby and never played after the first hour. The new pokemon are definitely an improvement this gen.

I mean, people are probably avoiding spoilers because, for once, there's a legit reason to avoid them besides just new pokemon designs :P.  

I've heard that it runs like crap on original 3DSs. Is that true?

All 4 gen 5 games were excellent in that regard, imo.

Finish the second trial, having a good time with the game.

The only con with the game so far, is that I feel the need to follow the red flag, which has led me into exploring much less.

How exactly has it changed the formula? Still looks the same to me, wich is a good thing.

No x.x they werent good at all

If your talking about speed only maybe. Fire and Water starter are fine. 

I actually feel the need to explore more due to how nice the world is. knowing where I'm supposed to be lets me know all the areas I should explore before arriving

Nice, you have more self-control than I do.