PRO's: Great add-on. I love the orange error; excellent detail in icons and reasoning behind each one makes things easily identifiable. Bonus for having the folder icon to indicate physical location of bookmark and the ability to update links. I have tested several others and this is the first one that doesn't crap out on me after checking 24K+ bookmarks. Side-note it took 5:53:08 to check all 24,653 bookmarks. UPDATE: Something else I noticed this seems to catch more bad links then others. I ran Bookmarks clean up which I found is the only other one that would run thru 24K+ bookmarks however it didn't flag as much; roughly 2500. I ran Checkmarks afterwords and it has caught about 2800+ more and so far I have verified 600 as being bad or potential risks.

CON's: I only gave it 4 stars due to lack of ability to select multiples to delete.

Wish-list:
Sort based on error and/or hide certain errors only showing specific ones.
Select Multiples. e.g. using CTRL+Click a check-mark box to select random ones and check-mark a box scrolling down then SHIFT+Click to check-mark another box in-turn check-marks everything in between.
Save previous search to pick-up later if browser was to crash.