I've discovered too many issues with Edit Flow and WordPress 3.6 that I have to mark this plugin as broken until most of the issues get fixed. Here is my experience thus far.
After upgrading to WordPress 3.6, I discovered that I could not preview posts using the custom post status of Pitch. This took me forever to diagnose and figure out but it has something to do with the plugin not generating a revision which is shown as the post preview when the preview button is selected. I have demonstrated this bug to the developers at Automattic who are in control of this plugin and they are currently developing a fix. If you experience this problem with Edit Flow, I suggest you set your Default post status to Draft since the Draft post status works as expected.
There is another bug that’s in the core which if you’re quick editing the post to change post status or heck do anything from quick edit screen (then the timestamp gets saved)… Which means when you later publish the post and if you weren’t paying close attention… your post wouldn’t go out immediately… it was backdated to the day that you first made the quick edit.
I've also discovered that my Archive page shows a bunch of errors related to an Edit Flow function Warning: Missing argument 3 for EF_Custom_Status::fix_preview_link_part_two() in /home/blah/domain.com/wp-content/plugins/edit-flow/modules/custom-status/custom-status.php on line 1458 dealing with custom statuses. It's a mess and this plugin needs some serious love.