I'm having major problems with 4.3. I use a static front page, and the blog homepage normally at home.php or page-blog.php.

The following functions (and all their variations) no longer work properly in the loop in the blog homepage on any of my sites -

the_title
the_excerpt
the_permalink

If I create a WP_Query object inside any page template, let's say just to pull the last 10 posts, then all the titles and permalink URLs will be identical, and $post->ID (inside the loop) no longer pulls the individual post ID, but instead pulls the 'main' page ID, so every post in the archive now outputs the same value for post id, the same title, and the same link.