Windows Phone 8 and the two aspect ratios

This is a topic that I haven't seen a lot of discussion about but I was wondering how Windows Phone 8 handles the two aspect ratios it supports. For those that don't already know, Windows Phone 8 supports 3 resolutions: 480 x 800, 768 x 1280, and 720 x 1280. The resolutions 480 x 800 and 1280 x 768 are (15:9) and all of the WP7 / 7.5 apps were designed around this aspect ratio. However the new resolution 1280 x 720 is (16:9) which makes me wonder how old apps are being handled on screens of this ratio. Can anyone who owns the 16:9 HTC 8x comment on how apps are handled and whether there's any strange behavior. Thanks in advance.