I understand that some really old browsers have trouble with it, but I have some really big files so it's nice to be able to compress them.
I have my litespeed settings 'compressable' types set to:
HTTP/1.x 200 OK
Date: Tue, 27 Mar 2007 12:51:08 GMT
Expires: Tue, 03 Apr 2007 12:51:08 GMT
Last-Modified: Mon, 26 Mar 2007 19:16:53 GMT