Many of us use Tekla BIMsight or Solibri for IFC viewing, but there is another free option: FZK Viewer. It is just a 10mb download, unzip and go.

It has a Walk tool like Navisworks for easy navigation, and it can even export to a number of formats, including:
DXF (cool! quick IFC to DXF conversion anyone?)
Google Earth

Additionally, it can open gbXML and GML files. All in all, a handy piece of software to have if you are dealing with IFCs on a daily basis.

Oh, did I mention it can Merge .xyz point cloud files to the scene?

Build 771 direct link:
On opening an IFC, it produces a log file that can quickly locate geometry problems:

Download page:

Main page: