In Views versions prior to 6.x-2.13, it was possible to hide an empty field by checking the "hide when empty" checkbox. This worked as well when the field content was rewritten. Very intuitive, and simply an incredible powerful feature. I have spent the past thee weeks to develop a large number of Views which make heavy use of this feature. Since this worked even recursively (rewrite a rewritten field into another one, hide/replace segments if empty), it was to some degree even possible to write some kind of natural language sentences from database tokens.
In 6.x-2.14 this does not work anymore. If a field is empty and has been rewritten, the only the field content is "hidden" (which is anyway empty), but not the rewritten stuff around it. The new behaviour changes significantly how this feature works, and I consider this as a major regression since a previously existing functionality has been removed without warning (or understandable reason). Probably a lot of existing Views will break in nasty ways when the 6.x-2.14 release is being deployed.
For 6.x-3.x-dev there has been a lenghty request to add #1020540: Add a "Hide Rewriting if field is empty" option. I assume that the changes in 2.x came from the 3.x branch, and the (existing) fixes for the 3.x branch accidentally haven't made it into the 2.x branch.
However, please give us back the possibility to hide rewritten fields when they're empty!