I got this as a gift and only used it for two weeks. To be honest I think its much easier just heating bottles using hot water. You add water to the side tank, drop in the bottle, cover with the steam guard and then set the time. I had a hard time finding the right time. Often bottles would be very warm on the bottom but the mlik on top would still be cold. We used two different sized bottles at home which also was a pain (Medela after pumping and then ThinkBaby for milk transferred from storage bags). I found that the Medela 4oz bottles sat too low in the unit below the steam guard and the ThinkBaby bottles were almost too big.
Being sleep deprived it was often difficult to get the timer right. If I would set it for two minutes and then the milk was not warm enough it was hard to get the unit to start again for another 30 seconds. I think there might be a safety delay.
I personally prefer just using hot water. We have a Zojirushi 3.0-Liter Electric hot water machine on our kitchen counter and I found it easier to dispense hot water from that into a mug then insert the bottle into the hot water for warming. If you don't have a hot water machine and you are wililng to figure out the times then the Munchkin Bottle might be for you.