I just updated my site to WordPress 3.6. On the updated page of wordpress 3.6 it says that it makes your writing experience even better. I have been using wordpress since 2010 and I am one of their happy users.
Before I update my site to wordpress 3.6, I created a backup database first of my website. This is to make sure that if there will be problems in the update, I can simply restore the site using the backup database.