I rated it 4, because it does have it's downsides.
PROS: THIS really defines the idea of a "codec pack". It's truly an all-in-one, totally complete package that installs all the needed codec to play almost all types of audio and video formats. With this installed, I would never need to download any codec again.
CONS: It's not really beginner-friendly, since with a lot of stuff thrown in, you might have a hard time installing the codecs that you would need. The dashboard system does ease up things a bit, but without codec knowledge and which conflicts to which, problems WILL occur (though I only used the default settings for ACE, and everything works fine)
Overall, for me, the pros outweigh the cons, and this codec pack sure is a keeper. After all, for all my media playing needs, I only needed Zoom Player WMV Pro (with some Media Player Classic to supplement it).
Oh, and for those who think that uninstalling ACE MCP is VERY difficult and messy, maybe you wanted to try running a registry cleaner and restarting the computer afterwards?