Mists of Pandaria has brought many cool new things and 3 of the key features for me are the fact that pets, mounts and achievements are now becoming account wide.
Pets are becoming account wide to facilitate the abomination that has been labelled Wowkemon around the community. But that aside the benefits of account-wide pets is bitter sweet sure it will save us all buying a pet multiple times and enabling us to use hard to acquire pets on our alts. The flip-side is that as an auction house player I’ll have less opportunity to sell pets to other players in numbers. However, there are rumours of being able to sell battle pets and that may well be a better income stream than traditional pet sales anyway.
Mounts is pretty much the same deal and getting all my raiding achievement mounts on my alts will truly rock it also makes mount acquisition a bit faster if you can be bothered to grind rep with a faction on 2 characters simultaneously (Baradins Wardens/Argent Tournament). But the biggest win here for me is that Evlyxx will finally get the Baron’s Mount that my deathknight, Nobunaga got a while back.