Daniel recently moved his site to WordPress.com and had this to say in the comments of his announcement post:
I want WP.com to be good enough that I can sincerely recommend it to my friends and family, but in some cases WP.org has better features, flexibility, etc. There’s still work to be done; actually using our software is the best way to discover what needs to be done.
This is why every developer of a publishing tool must be a consistent and active user of the software. The best way to learn how to improve something is by using it regularly.
My site will be moving back over there hopefully next week. I just need to carve out an hour or two to customize a theme a bit and get all the content moved over properly.