When using mobile, the horizontal home screen is nicely laid out, with most major features of the full page visible.



But when you flip to vertical, you lose a lot of the info: timestamps, latest thread, etc.



Within individual threads, the horizontal layout is also pretty good.


But when you swap to vertical, user info is compressed and missing. There's a waste of empty space to the right of the username.



Edit: Also, some more issues:

Sigs disappear in vertical, which is fine, but you may want to throw a border or a few line breaks between the end of a post and the edit, reply, quote buttons. It feels a little text wall-ish.

The floating mobile quick post editor is a little too large. It fills the whole screen and makes touch manuevering a hassle when you're trying to move the cursor to the edge of the screen. Not a huge problem though as you can always click more options and go into advanced posting.

 

That is the lowest zoom for Chrome when not using the desktop site (which is a viable solution for all these issues). You can move in, but not out any further. It may be different for other browsers.

 

The username stuff is fixed. Vertical homepage compression still wonky. It seems like the info is there, but the forum boxes just have a maximum size, so it gets cut off.

edit new reference image @Lord Ravenclaw