I have used this thing dozens and dozens of times, each time thinking it would be easier than a MYSQL import. I am almost always wrong.
Image import fails far too much. Often it will show failed imports and they are actually imported. And if the xml is large, count on it failing.
As stated by others, this is a simple function and should actually be core.
Meh, I guess I should make my own and quit crying about the issues with this thing.