My wife got me one a few months back. It mostly works as advertised, though a couple of times it inexplicably failed to record a show I'd scheduled -- a problem I've heard isn't uncommon. The app interface is quite clunky, failing to follow some Apple GUI principles, but not that hard to figure out eventually. And its features are pretty limited, but you can get some of the missing functions (e.g. starting a playback somewhere other than the beginning) by opening the saved files in quicktime or iTunes.
I don't remember where they are now, but there have been a few negative reviews on the web that thoroughly discussed these issues and others that didn't matter to me , so you might read those before plunking down the money. But for me, the Radioshark does exactly what I need: records radio shows I can't be there to listen to.
Oh, and be sure to download the most recent software update; it eliminates several problems with the first version. I do hope they update software again soon, though -- it could be a lot more user friendly.