A lot of sound cards supported. Under Redhat 5.2 I could not get any sound from Real Player using the standard kernel sound driver. After installation of OSS sound was working with Real Player. Sound is not yet consistently implemented. Some applications like TkDesk or RealPlayer use the standard sound mechanism, others like Enlightenment reimplement their own sound system to be able to play several sounds at once.
Some games temporarily lock while playing a sound.
Expect more supported sound cards in the oncoming 2.2 kernel. The greatest utility of all times. File manager under X-Windows. Multiple panes windows. Contextual menu for files, quick view, change file attributes.