'Many of the auto-create thumbnails from the old site are some of the fuzzy thumbs that members have been complaining about, and members are encouraged to update those.'

just keep in mind, that also as of today, if you update your thumbnails AND you have any kind of formatted text that you wrote about the image, etc., that the formatting is lost and all your words will get shoved and word wrapped together. but i'm sure that the formatting thing is yet another thing they are working on, so you might want to hold off until that's fixed too before changing out old, horribly distorted thumbnails.