I still think Speaker for the Dead is worth reading, and there's no reason you can't stop after that.

Personally, I also loved Speaker for the Dead and Xenocide even though they are very different from Ender's Game. The ones that came later I also enjoyed but not nearly as much as the first three.

He didn't write himself into a corner; he was trying to shoehorn in his religion.

This is true and being downvoted. The shoehorning didn't really show up until Xenocide when he was softballing himself counterpoints and whiffing them mightily. It was sad seening as how Speaker for the Dead was so spectacular.