There's an interview with Dave Alvin in the new issue of No Depression magazine in which he talks about the experience of getting to see some of the great figures in blues and country-music history perform live. "The tragedy of learning this music from records," Alvin says, "is that you don't get the full effect with a lot of artists, the physical feeling of being in the presence of someone like that. If you had any soul at all, you just responded to them."
This is what you're missing when you've gone this long without seeing B.B. King live. You're missing a chance to hear somebody who absorbed the blues tradition from the people who created it. You're missing a chance to hear somebody who defined the most widely known and deeply personal guitar style in the history of his musical form. You're missing a chance to connect with the music that runs so deeply in his soul to this day.
Remember, this show is free. Realize also that you're getting the chance to catch Dr. John, a legend in New Orleans music, and the very talented Shemekia Copeland on the same bill. There are very few good reasons to miss this show.