Before everybody clicks on this and gets too excited:
1. The CEP is not a bug-fix package. It is essentially a collection of six years worth of custom content that has been tweaked, tested, and made to work together. If you are not playing a module that requires CEP, or aren't planning to create your own modules, you don't need to download this.
2. This is important because it's a 786 MB download.
3. For module builders thinking that CEP content would be cool to put in their own modules, including CEP content is not as easily as you think as development and scripting is a little scattered at v 2.3. Also, again you're asking that anyone who plays your module download another 768 MB file.
Not to bash CEP because it is a pretty mighty piece of work, but it's basically only for hard-core NWN players and designers.