That depends on what you want to do with asterisk. If you want to do anything more than just play with it at home in a limited sort of way, i would certainly recommend learning how to do configuration by editing the config files with a text editor. Apart from anything else, if you end up doing remote administration (via ssh, for example) you will be glad you don’t have to rely on some clunky gui stuff to edit the config files with and to control the system.
You will also always find you can do some things with config files that you can’t do with gui stuff. This is likely to be the case for a few years to come, i’d say.
If you learn how to do the config at the basic level, you will understand much more about what’s going on - even if you don’t use it all the time. I’d go so far as to say that if you don’t learn about all the config files and command line stuff, etc, you will never be a very good asterisk administrator. The same goes for system administration in general.
By the way, if you don’t already use it, i’d recommend learning how to use the vi editor, if you’re ever likely to want to do remote admin. Don’t rely on some gui text editor, they’re not a lot of fun to use over a network - even a fast one.
Sorry if you already know about most of this stuff - maybe there are others reading who don’t.