Finis Tempo Trainer

Was wondering if anyone here uses one of these devices in their swim training? It's a small, round electronic device that you slip underneath your swim cap near one of your ears. You can set it to sound a "beep" at a certain tempo to keep pace with your stroke. I met with a swim coach a few weeks back for a stroke analysis session, and he had me use one of these things. I found it to be quite helpful in maintaining a set pace with my arm strokes. I'm thinking about purchasing one for my own use...so I'd like to hear other people's opinions of it. Thanks!