I just downloaded iBlogger for my iPhone today, which is where I am writting this post from, and I have some mixed feelings about it. So far it has functioned as advertised, yet it has some quirks.
It is definitely better than posting via email. I always seemed to have problems with line breaks when posting from email, so this is step in the right direction. The editor works well. I don't mind the lack of horizontal typing, but that has never really been my preference. And, due to the limitations of the mobile interface, you can't format your text (font size, bold, etc.), but that isn't the applications fault. This is also probably why XHTML markup is shown when editing existing posts. One other limitation for Blogger users is the inability to post photos.
So, it does work well for new posts. Working with old posts is problematic. When it initially loaded my existing blog posts, it took the load time and date rather than the time and date the article was actually posted. So, posts from a week ago were dated today. I thought that this was no big deal, but when I edited a post it saved that date and time instead of the original (or even instead if the current). Therefor, when I corrected a typo in a post from last week it changed the time to this morning, effectively making it the most recent post.
One other curiosity is on the blog posts screen. The scrolling is not fluid, it's slow to scroll and feels like it must be doing a lot of work in the background.
I do like the ability to add tags, the interface is clean and efficient. There is also a neat feature that allows you to create a link to Google maps of your current location. And there is an option to automatically add a signature, though the default signature contains a link to the iBlogger website, which is a mild irritant for a paid application. The signature is enclosed in a div, so I think that you could customize the style of it.
You can also add links. It is a little awkward to use, but it gets the job done. It seems to add the links at the bottom, so when you are editing an article you would want to exit edit mode at the spot where you wanted the link. Add the link and go back into edit mode and clear away the unneeded spacing.
In conclusion, I think that I will continue to use iBlogger to add new posts when I am on the go, but I am hesitant to use it for updating existing posts due to how it changes the timestamps.