It does work, and for us it’s worked very well. I’d recommend it to anyone that needs something more than Simple Commerce can do.
I used it on a very large EE e-commerce project, and I have two more smaller ones that we’ll be using it on as well. The existing project has a library of 25K articles/photos for viewing online as EE entries, then available for purchase/download along with an overly complex (!) tiered membership/billing system.
There’s a new release pending that might have made the initial setup process easier (we had to have some custom scripting done since we had so many archive entries that had to be added as downloadables for FoxEE that probably would have been easier with the import feature they’re implementing), but it works very well. We’ve been up and running with essentially a beta version since January, and aside from the occasional wrinkle, it’s worked pretty seamlessly once everybody got used to the process. We had one issue related to an incremental update that rankled downloads for a couple of days, but the client was able to still record the purchases and deliver the files manually until a fix was in place.
As for ease-of-use, I guess it depends on what you’re using it for, and how comfortable you are sorting through the various entities (FoxEE, EE, FoxyCart, and whatever gateway you use) to get things working the way you want. Ours wasn’t particularly easy, but that had less to do with FoxEE than the particular complexities of the client’s setup.
The guys at HCC have been very responsive whenever I’ve had a question or issue, and seem to be very committed to packing it as full of features as we might need down the road.