Forum upgraded to the newest shiny version. There were too many changes to the templates that actually add features that it will take awhile to put it back together.
If you want, you can still change back to the sepia theme. It is called "lockmor2" and can be changed in your profile. It will not, however, have any of the new features that the new one has.
Some of the notable changes in this release are:
Edit a post without page reloads
Double click to edit topic subjects on message index (Need quick moderation enabled)
Added new search features including
Search within a topic
Search within personal messages
Search participation levels are now shown
A new feature to create a custom index for searching messages, and more.
Most Online Today and Most Online Ever has been added to the Info Center.
There are TONS of other updates that aren't worth listing but this theme is much better than the other. Their default theme matched winter almost perfect so changed defaults for everybody so it is more seamless in between them.
Again, you CAN change your themes in both sections to whatever you wish. The option is available, but this is now the default.