Some folks may be confused when they go into Photoshop CS6's filter menu and don't see many filters that they are used to seeing in the menu. We've pared down the list to clean up the menu a bit, but the filters you know and love are still available.
Firstly, they are made available through the Filter Gallery -- Filter > Filter Gallery.
If you did not know this, just knowing that they're neatly tucked away in the Filter Gallery may be enough to satisfy.
If you'd like to see all of the filters in the Filter menu again, follow these steps:
To change to the legacy filter menu:
Navigate to Preferences > Plugins
Check the box for "Show All Filter Gallery Groups and Names"