Can you point out specifically what makes it hideous?

It's probably a personal aesthetic, but the variable stroke widths make it look cartoony. It's also got a tendency to big loops — the a, p, h, and g in the sample all have very large, arched, oval shapes (this is probably what they're referring to as the large x-height). That makes it look exaggerated to my eye, and doesn't help the cartoony appearance either.

But if it is a personal dislike and other people are fans, I can't object. It wouldn't be the first time I disliked an Apple initiative that turned out to be very successful.

The big loops seem necessary to me, at least when staring at the 8pt size on my retina screen. It's the same sort of contortions you go through to make a "pixel" font look good at 8x8 or 5x5, or an icon look good at 16x16—abstract overemphasis to survive reduction.

I think, if the font didn't literally have to be continuously zoomed in a lot of places, they would just lose the overemphasis at larger sizes.