I bought the Zeno Hot Spot which I've been using for about 2 weeks now. Unfortunately it broke couple of days ago :(
Everyone look at my pimples! >.<
Anyway, the Zeno Hot Spot is designed to work 80 times, at $40 it equates to $0.50 per treatment per pimple. The device has 4 LED lights that indicates your usage level - you start with 4 lights, as it goes down 1 by 1 you'll know how much you have left. Unfortunately I still had 2 lights left (which is probably around 40 more treatments), the Hot Spot broke and stopped turning on :(
I tweeted them and they said to email their customer service, which I did, and am currently waiting for their reply.
My thoughts on this device so far is that yes, it does work very well on smaller pimples - they go away pretty much over night, or the next day. Bigger pimples obviously take longer to heal. The Hot Spot does not work on whiteheads, blackheads, and cystic acne.
I will write more on this after I hear back from them, I don't want to write too much when I haven't fully used it yet... =p