I recently imported a bunch of feeds from Google Reader. I typically sit in the “Unread” view, but when I popped over to the “All” view to check a few things, I noticed a number of feeds have an orange “!” next to them, indicating a problem. It is absolutely wonderful that I can click on the feed and get a helpful tool to see the recent HTTP error codes, with an option to re-scrape the site to get a new RSS link. Many of these were for blogs that no longer exist. A few were for blogs whose feeds had moved (e.g. off of FeedBurner), but I never caught the change.
I would have never noticed many of these broken feeds – they’re hidden away inside of closed folders. It would be nice to have a mode that lets me see only the broken feeds and repair/delete them.