He's a really skilled player for sure. If you only know the pop songs, I'm not at all surprised to hear you say that it's startling to hear him get after it on a guitar. That said, I blow hot and cold on his musical choices - sometimes they blow me away and other times he leaves me wanting more.
John Mayer - Opened My Ears
I've heard John Mayer on the radio over the past years. I like his pop songs but was not overlay impressed to be honest. I recently watched via You Tube - Live in Los Angeles, Live on Letterman. Holy cow!!!! I heard numerous songs not played on my local pop stations and remakes of the songs I do know that really captured my attention. His live performances far exceed his radio played material. The 2008 Live in Los Angeles concert was broken up in three sets - acoustic, blues like trio, and the full band. He's also appeared on Clapton's Crossroads concert. His guitar skills really blew me away. He's certainly one of the premier talents of his generation. I would suggest given more years and material he'll solidify his place to the likes of Simon, Dylan...... That's a bold statement but he certainly has the talent to reach that mark. I hope to see him live someday!!!!