I imported a small Tumblr with this plugin to try it out. A test run before the real thing.
It works quite well but of course there were some issues with the titles.
I think the YouTube videos could be handled better.
If the Photosets posts don't have a post title the gallery will be created but it will be empty with no images attached to the post. (Maybe just me but I tried a few times.) With a title it posts as a gallery as it should.