I've done migration from Magento 1.6.2 to 2.0.2 with the official data migration tool.
In general it worked. But I cannot edit any products (no fields are shown) and I suspect its because all of the new system attributes (like category_ids) and the "Default" attribute set are missing.
I just don't know why those attributes get deleted and what to do against it.
Any help is much appreciated!