I was dubious abour buying this because of the bad reviews on here. I risked it however as it was in the sale an dirt cheap.
When I first started using it I felt a bit stupid, thinking a boiled kettle would be cheaper and as good, but having used it for a couple of weeks I've found it to be fantastic. I set a countdown timer and pop it into the warmer. No having to boil kettle, find bowl, pour, work out how long to leave it........
To operate you put some water inside the water, turn it on, crank the temp up to 3 (what 1 and 2 are for I don't know), time it for 3-7 minutes depending on amount of milk in bottle, turn off and remove milk once time is up. I'm sure there's fancier warmers on the market, with timers inbuilt, or turn off once the time is up, but this one suits my fine.
I'd pay full price if it needed replacing.
EDIT: After a month or 2 of using this we gave up and started microwaving the milks. I know this makes us bad parents, even though we shake well after taking it out, without fail, and nutrition loss is proven to be very low.