How could this not be good?

[Steve Piranha 28,787]

Making a well-paced movie with a team that usually makes episodic cartoons? Yeah. That'll end well.

That's probably why they are co-working with the writer of Toy Story 2 and Mulan 

[NullAccount 287]

I could think of only two ways it could be bad. They could reintroduced the characters for the people who happen to be watching the movie but have never seen the actual show, so most of it would be characterizing all the ponies. Another way is if they made it one big commercial to make people watch the show to actually enjoy it fully. I trust the staff to do a good job with all of this though.

[cuteycindyhoney 13,283]

Emily Blunt? I have the sudden idea that maybe Twilight's mom will finally get a voice!

[cmarston1 5,952]

What Could Possibly Go Wrong?

 

Fixed the title for you.

Pretty much this.

Asking how this movie could not be good is basically asking for things to go wrong.