A really valuable addition to the blog would be more control over the 'Custom Feed' and 'Recent Posts' display.
Other CMS platforms allow feed controls such as number of columns, if an image will appear in the preview post or not, and if the image does appear automatically resize it to a thumbnail so that it's not cropped.
General resizing for better placement of the feeds would also be great, such as scaling it all smaller and not having to take up the entire width of the layer.
The feed and posts displays, and even the Blog itself, may also benefit from being able to order the Categories. For example all of Category 1 is displayed (in some sort of sort order like date), followed by all posts from Category 2, and so on.