We have an Oxycare 3000 that DH got from the Ortho. He loves it and thinks it's just awesome, but then, he's got braces.
I've tried it, and I'm not sure what I'm supposed to do with it besides make a mess. So if I had it for me (no braces) I would probably return it, or never use it again. ETA - it's not the unit itself, as it's very easy to use, and does it's job, but I just don't feel like I get any benefit from it, if that makes sense. I've had better results with the Sonicare toothbrush and regular flossing.
Did your dentist/hygenist recommend you get one?