Three in one means you can use either just the top, just the bottom, or the top and bottom if you are sterelising full bottles. Means you can take it apart to easily sterelise things like dummies when you don't need the full thing
REALLY easy to use its so self explanatory how to put bottles in with all the little pictures where each bottle & top goes
Takes about 10 mins to do a sterelising cycle I think (I haven't timed it but its around that)
Cannot switch it off mid sterelise, once you push the button its on and remembers that it was going even if you kill the power as my husband learnt when he turned it off and on again. You have to let it run its cycle, have its 10 mins cool down time then you can use it again.
Indicator light lets you know easily when its doing its stuff and when its done!