I've been to a couple concerts, though not since the latest album, and I would recommend them to anyone who loves good music.
By the way, here are some other threads on Sigur Ros:
http://www.tfproject.org/tfp/showthread.php?t=62060
http://www.tfproject.org/tfp/showthread.php?t=94079
http://www.tfproject.org/tfp/showthread.php?t=98170