The empress of graphic novel bloggers is Heidi MacDonald at The Beat: http://pwbeat.publishersweekly.com/blog/

Chris Butcher from Toronto's legendary The Beguiling comic shop always has thought-provoking opinions: http://comics212.net/

Tom Spurgeon at The Comics Reporter has erudite commentary: http://www.comicsreporter.com/

Brigid Alverson's team at SLJ's Good Comics for Kids provides an excellent overview of the kids comics scene: http://www.schoollibraryjournal.com/blog/540000654.html

The tireless Carol Fitzgerald and editor John Hogan produce The Graphic Novel Reporter, aimed at general readers: www.graphicnovelreporter.com

These are just a drop in the bucket of comix blogs....