There are two versions - the light free version and the pro version. The free version works pretty quick, but is limited in the variety of output.
I downloaded the pro version. Creating an HDR required just a quick drag and drop of relevant files from Aperture. There are 1-click styles similar to Photomatix Pro, but many of the effects seem contrived. I was able to get better results (at least the ones I like) by digging into the adjustments menu.
At $29 the pro version is a good deal, but the workflow is not as smooth as the Photomatix Aperture plugin.