A variety of RvR changes have been made as well, such as new Keep Defense mechanics. This new mechanic requires keep defenders to destroy the attacking war party's battering ram, at which point the siege will "briefly shift to a 'Successful Defense' state." The defending troops will then receive a buff, intended to allow them to push back their attackers. Once the defenders push the attackers out of their keep area, however, the buff will quickly fade, putting the battle back on a level playing field.
For all of this and more, players can check out the full patch notes and get a firsthand look on the public test servers.