I own a Clarisonic device. I used it all the time before I was on Accutane. I absolutely loved it. It kept my acne pretty much at bay and I only received small breakouts here and there. My skin was really smooth from it too. I'm on Accutane now because I want to permanently stop getting any breakouts. I'll return to using my Clarisonic once my Accutane treatment is over. The only disadvantage is the cost of the device and the brushes, which you'll need to replace from time-to-time.
I love my Clarisonic. The brushes are expensive and I alway forget to charge it because I use it in the shower (yup, it's waterproof) but other than that, it's great. I definitely think it has helped eliminate small acne breakouts I used to get every once in a while. I use Obagi's salicylic face wash and my Clarisonic every night and my skin feels great afterwards. I usually apply Oil of Olay face moisturizer after and I've been very happy with the way my skin looks.