We're using this at my work for a product recommendation engine. It's essentially a wrapper around Apache Mahout (which uses Hadoop). It make the whole Hadoop/Mahout setup much more accessible, but it still has the same drawbacks (sucks memory like anything, lots of overhead to ramping up the jobs)
It was pretty straight-forward to implement and has a nifty backend to it as well for managing the algorithms.
We're working on using it to recommend user-created events. Just getting started though, hopefully we'll have something to show next month. Haven't shown our site love in awhile but some info is at http://wobbleapp.me.