It sure looks nice, but I feel too much screen estate are used to show feed list and article list: while I haven't measured it, it looks like only around 1/4 of the area is used for article content. and the article content is why you want to use a feed reader in the first place.

For me to consider using this feed reader, the area for the actual contents should have at least the same area as the article list. Possibly even swap the two areas.