it's kind of similar and kind of not. It's a plug in for starters. It can be multichannel, it can load multiple samples at one time plus it has internal effects that you can programme for each splice.
It doesn't import or export to rex files, however, you can export your midi files and create groove templates from it.
The only thing I did have a slight issue with is that it used to be a bit flaky in operation crashing out quite a bit. It got a lot better but it even got to the point of corrupting my logic files so I chucked it and went to NI Intakt... not quite as intuitive, but easily as powerful. I say used to as I think it is much better and is happily accepted by Logic's AU manger these days.
Have a look here for more info, the video tutorials are pretty good :)