EAX also does enviromental audio, so if you were listening to music, you could set the enviromental audio to 'theatre hall'. i never use it though.
jorsoft is right too about EAX sounding weird in old games. UT2004 is a great example, since it uses EAX to 'emulate' 3D positional sound, and it doesn't work very well, eg. your rocket launcher fireing is too loud, and when the rocket explodes, you can barely hear it. and sounds comming from the rear, sound like their out of a telephone and come mostly from the front speakers.
Splinter Cell: Chaos Theory supports surround sound natively and uses dolby digital encoding, so the sound comming from 4,5,6, or 7.1 channels is crisp, clear, and unmuffled like in UT2004. Chaos Theory also uses EAX to create an effect which voices comming from a room nearby can be heard through an echo through the hallways leading there. and IMO, chaos theory is THE best example of outstanding surround sound I have ever heard.