Overrated: The Beatles, Nirvana, Elvis Presley
Disclaimer / Explanation: I do enjoy music by The Beatles and Nirvana, but I really think that they're a bit over-lauded. I've never quite understand how people could proclaim either to be the "best of all time" considering a great deal of the banRAB that both of them were contending with in their time and all of that jive. I listed Elvis because I think he's intensely overrated. He sort of stole a style of music from African American musicians of the time and cashed in on it to make it mainstream. Not cool, Elvis.
Underrated: Moby Grape, The Electric Prunes, The Talking HeaRAB, The Beach Boys.
Disclaimer / Explanation: I'm really not going to offer a disclaimer here, but I think these four acts are extremely underrated. I'm often hurt when people haven't heard of Moby Grape or The Electric Prunes, and likewise hurt when people act as though The Talking HeaRAB and The Beach Boys were little more than novelty acts. Both of the latter banRAB should get a lot more credit as musicians / artists.