It's pretty bad in that it forces you to pronounce lots of awkward "x"s in names that were meant to be euphonic. But yes, the main issue is that a translator making such an epic mistake can't be trusted to maintain accuracy or faithfulness elsewhere.

Also, a separate review criticism is that the translation fails miserably to capture the cheerful, whimsical style of the original narration, instead giving it a completely different and much less gripping narrative voice that ends up clashing with the content of the story.