No course on rock bass playing can ignore John-Paul Jones of Led Zeppelin. In this bassline, which is meant to recall "Dazed and Confused," I believe that you'll find this seemingly simple and slow bassline a real challenge.
We're first introduced to the "slide" as we slide our hand up the fretboard to play the G on the 15th fret of the E string, playing all of the notes on the E string for a more sustained and fuller tone. Try playing it on the other strings and then only on the open E to see what I mean. Having to play a bassline that's this slow points out areas that need improvement, with any tendency to bend the notes sharp or add bad sounding will be highlighted. Give every note its full value with as pure and even a tone as possible and this bassline will sound GOOD!