Groundspeak has supplied a brand new API to connect to and the old one will expire I'm afraid. The new one offers new possibilities, but converting it to use the current functionality wasn't easy.
There are simply too much improvements and fixes to mention, so I won't sum up all.
- Searching in the area or opening a cache on code is made possible in the pro version
- The images of the cache are now no small thumbnails, but large(r) pictures. Clicking will bring up the Android associated viewer. Any EXIF details are already in the list.
- The message bar wasn't showing in the cache detail view; now it is.
- No more external ads for the free version
- Fixes in the selection of multiple caches
- Map will show in most of the times directly on the detail page.
Note that the authentication for Geocaching.com has been changed due to the new API. The token is only valid for an hour. So if you do not activate notification, you'll have to login a little more often...