This is an error I reported about Oct 2010, I've been brushed off by support, it seems there are no plans at all to fix it.
Situation:
Export WP blog to xml, selecting all options.
Open new WP blog, import xml, selecting all options.
Example:
original: testsinglepost2.wordpress.com
new: testsinglepost.wordpress.com
Expected:
New WP blog should be identical to old
Issues:
* post featured image - not preserved, deleted
* gallery image captions - not preserved, deleted
* gallery image alt text, etc - not preserved, reset to post title (not slug)
* gallery image order - randomized
* gallery images are doubled. a post with 1 image will become a post with 2 images. however as above the order is randomized making it impossible to manually delete half the images
* inline images - randomly linked to old post - see testsinglepost.wordpress.com/2011/03/20/test-post-for-transfer/
the inline image points to the original link. strangely the alt text is preserved here.
* Note that in the media library, all the new images are now named "Test post for transfer", making sorting or searching impossible
* links to other posts are also randomly linked to old post or changed to the new, there is no way to predict which it will be.
Conclusion:
As a programmer myself, 80% of these look like simple fixes, it shouldn't take someone working on the code more than 2 days to fix them up. As a person who has waited for over 6mths, I've considered hand editing everything from scratch, but deleting half of 2000photos and reordering/recaptioning them sounds stupid even for me.
Addendum:
After a few mails with support, they introduced the domain name change feature. However this also had a few of the same issues, and after a few tests I wasn't confident enough to risk losing any data to a one-way operation.
Also, the domain name change does not allow you to move to a WP.com name that you already own, which rules out everyone who tried the import already and found it broken.
The blog I need help with is iliodos.wordpress.com.