Sure, webmin will do the job but it is very limited and does not have all the features of those paid control panels. To be honest, I use webmin in conjunction with cPanel because somethings like cron are easier to manage in webmin. I could do it from shell but I like the interface that it uses for cron and perl modules.
That's fine, I don't blame somebody for wanting it free and if it works for him then that is great. Back in 98 before we had all these fancy control panels I ran webmin to setup http sites. Things were a lot harder back then as myself and my team were new to Linux.