I'd discovered Metroid Metal nearly a year ago purely by accident, searching for the original NES' Metroid tunes. Totally blew me away from the first few guitar licks. Thus, I knew what to expect when I went to see them at PAX '09.
I was wrong.
They were more metal than ever! MM came out and melted our faces off song after song. I was pretty close to the stage, too, so I felt the full force of each note as it shredded off another layer of my flesh. One of the best shows I've been to simply for the amazing energy from the band and the fans (myself definitely included there.)
I picked up Varia Suite at PAX as well as a sampler of other songs from bands the MM members are in (Arm Cannon's cover of The Mighty Morphin' Power Rangers theme is to die for.) If you have the chance to see Metroid Metal play live by all means do so; you won't be disappointed.