For me, one of the most annoying tweaks in OS X Mountain Lion was the change of the default save location for many of apps I use on a regular basis. Any app that uses iCloud now displays its save dialog box differently than it would have before its integration into OS X. Due to this, upon saving files in many applications, instead of being presented with a view of the filesystem, the default save location is now just “iCloud”, and saving the file anywhere else has become somewhat of a chore. Thanks to some Terminal commands, though, this behavior can be reverted to its pre-Mountain Lion state, as i’ll show you in this video.
defaults write NSGlobalDomain NSDocumentSaveNewDocumentsToCloud -bool false
defaults write NSGlobalDomain NSDocumentSaveNewDocumentsToCloud -bool true
Source: Mac OS X Hints.