BitchX (aka BotchX) more or less sucks, depending on what you're running it on and what your needs are. (This is a fact - of course, that's true for just about everything else. =)
It was, as said, originally a kewliness-adding script for ircII that has grown into a client of its own. It was written by people called Trench and HappyCrappy, and patched to the client itself by Colten Edwards (aka Panasync). The home page is at http://www.bitchx.org/
Personally, I never liked it much - mostly because for long time, åäöÅÄÖ and other latin-1 characters never worked (apparently sacrificed on altar of ANSI). Apparently later versions helped with this.
Also, if you're trying to run it on real vtXXX terminal, the ANSI spam is reported to be too high to be handled by them at times. (So I've been told. I have not tried it. The oddest part was that some newbie told the guy who told this factoid in Usenet to upgrade the thing...)
If you want a truely l33t client or just want a BBS retro feeling, BitchX is the way. Others should use something like ircII or EPIC or, better yet, irssi (which, BTW, has a BitchX-look-alike-theme and also supports a real scripting language =)