When you click the "add/show comments" link, the text field for writing new comments is automatically focused. This makes a lot of sense on a regular browser, but it has a very annoying effect on mobile devices.
Each time I click the link to read the remaining comments the on-screen keyboard expands. Most of the time I don't want to write a comment when I click that link, I only want to read them. This is especially true on a mobile device where writing is much more cumbersome than on a regular computer.
On a mobile phone I would of course use the mobile version of the site, but on a tablet the desktop version is the preferred one.
The automatic focus should stay for non-mobile devices, but it is very annoying on tablets and should be removed there.