I may need to change the WordPress theme that I use for this site. For some reason quoting material – which I do a lot – does not work very well since I upgraded. My apologies if there is any oddness while I experiment!
UPDATE: OK, I have reverted. The same problems appeared in the default WordPress theme. It seems that WordPress 3.6 is broken.
When you press “quote”, quite often it just inserts a new paragraph. It often does not unquote a quoted passage. And so on. Blockquoting is a fundamental issue, and WordPress have broken it.