Here's my list of gripes with the default client:
* How do I change the view to just show the feed's headlines instead of the headlines and the content? (The list view that google reader, net news wire, and liferea have).
* How do I create an "all unread items" entry in the feed list?
* How do I mark ALL feeds as read?

The default RSS reader just seems to be a proof of concept, not an application that someone who has 50+ RSS feeds can use.