Depends on what you want to do with it. It might be useful to install webmin or virtualmin. Both can help you do the things you already know more conveniently, and both can expose you to some configuration options you didn't know existed.
I've used virtualmin in the past, and while it might provide a certain level of convenience, resolving server related problems becomes, well, a problem. It pays to learn to do things the hard way when the inevitable server issues arise.
One of the things I like about virtualmin and usermin is that they do very little in terms of non-standard config file manipulation (relative to, say, plesk). Agreed that resolving problems from usermin can sometimes be problematic, it is convenient for a lot of things too.
Being able to use the proper tool (control panel or straight command line) is best. I'd found that using a tool to do X would let me then go look at the config files before and after X to see what/how the tool was doing - that was a great learning exercise for me. Might not be for others though.
