How does one properly play it?

Your phrasing is weird. I would say that's completing or beating the game, you can do either by playing improperly

FFXV will be embarrassingly bad.
X will be amazing.
End of the debate, can we go to lunch now?

Here's an unbiased take on it:

Both games will be amazing. 

Play the games long enough to understand the strategy. If you can't give proper examples of what the stategy of both games are (like myself and a few others have) then you probably haven't played them enough.

It will LOOK amazing. I will give you that.

I think the best XV can hope for is to be underwhelming based on the hystory of Square-Enix. A look at their games like XI, XII, XIII, and XIV. Popular opinion would show most people think some are okay, while others are downright awful (the awful being XI, the XIII trilogy and the original release of XIV).

The people who hate Xenoblade are few and far between, with a lot either not knowing what they are talking about, or never really playing the game. X is destined for greatness.

Shawarma sound good?

So because S-E made some arguably disappointing games, FF XV will necessarily be the same?

That's not a biased stance to take at all. -__-

That's how people can become pleasantly surprised. I agree games can come back from mediocrity, look at the Xenosaga series. BUT, I don't think it's unfair to say a dev makes less than stellar games based on history, no.

Also Final Fantasy X was an AMAZING game. But it was also made by Sqaure, and along with the original Kingdom Hearts they were the last games made by what they WERE. Square was an awesome company filled with talented devs and great leadership, but that's not what Sqaure-Enix is.

I agree, what can I add?

Sounds great, let´s go, I will pay.