The package descriptions as given in equo and rigo are not very detailed at all. While this may not be an issue when you know exactly which package you want already, it makes the package manager much less useful when you are trying to find a package to accomplish a specific task.
A one line description is not enough to determine what a package does, and in many cases, it's not even enough to determine what all a package does, or does not contain.
Compare: http://packages.sabayon.org/show/chromi ... 5,standard
or even http://packages.sabayon.org/show/cacti, ... 5,standard
The former focuses mostly on technical details that, while important, are details that the package manager mostly takes care of for me. The latter gives me immedately useful information that actually helps me make an informed decision about whether to install the package or not, without having to try it and see.
Further, in general, the search experience is really good, but the package browsing experience is lacking. In the event that you don't know exactly what you are looking for, the available tools for finding it become very awkward to use - for example, the results in rigo can't be sorted, drilling down into subcategories requires manually editing the search terms, etc.
IMHO, These are the sort of shortcomings that may be only minor friction to an experiences Gentoo or Sabayon user, but they are major pain points to a new linux user or (in my case) someone moving from another distribution.