I just purchased iBlogger from the iTunes store. So far, my experience has been positive. I'm actually typing this post on it.
Installation was as east as any iPhone application, and configuring it was as easy as pointing it at a provider and supplying my credentials.
I'm hoping this will make it easier to keep fresh content on my blogs, since the inspiration usually hits when I'm not in a position to pull out my laptop.
I'll update this post with further experiences as I try it out.