Its useless to say whats a good CMS and what's not without first even stating what you folks are using it for.
FYI I am using vbHome for my front page news , vbLinks Directory v2 for my links section , vbArticles v0.3 ( doing this hack btw ) for my articles , reviews and interviews section , Photopost v3.3.1 for my gallery.
And vb for my community forums of course.
Now everything is integrated ( photopost uses the vb user database but still got to do some slight design to make it look totally blended with the rest of your site ).
So basically you get one whole complete site going - on vB.
Who needs any other CMS

I personally haved used Postnuke for my site and eventually decided against it because its way too bloated for my needs.