One of the first challenges to show up is with Private Journals. To use the import tool, you'll have to make the journal public. After the import is done, and you have a working blog, you can make it private (select friends can read it), or you can make it closed (nobody but you can read it).
If you have a private journal, and it has comments that were made while it was private, you might want to hold off on making the journal public.
Bear in mind you decide to make your Journal public, all comments added while it is private will be deleted. Comments posted to a private Journal are written with the expectation of privacy.I'd be surprised of Blogger leaves this as an open issue, but let's wait until they can acknowledge the situation. You have until 10/31 (and possibly later).