I used the plugin successfully. But yesterday, after changing several buildings in JOSM. Import under qgis with the plugin does not work anymore. The buildings are in the layer point! Do you have any idea?
The reason for the missbehaviour is that Openstreetmap have crossed the border of 2^31 nodes: http://wiki.openstreetmap.org/wiki/64-bit_Identifiers, making it necessary for all programmers to change ids form int to 64-bit-int. I guess that is not yet implemented in the plugin. It will be rewritten for QGIS 2.0, so you have to wait until that is released.
Here an example of Mapnik map:
and what the plugin renders: