If the hard coded solution works for you, that's perfect! I mentioned the Google Publisher plugin becauseI I sometimes find it easier to install a plugin than to copy and paste code as you've done. Google's plugin also offers other options that you may find interesting if you plan on increasing the number of ads on your site.
As per the "Beta" tag, I wouldn't worry about it: most Google products remained in Beta for a couple of years, even long after they had become a stable product :)