yep, I do room temp bottles too and my DS has never complained! Cooled boiled water, into his bottle and into the fridge until he's hungry. I do give it a real quick zap (like, 25 secs) in the microwave if I'm home to take the cold edge off. Otherwise, just serve as is if we're out. I like to give his formula a bit cooler anyways if the weather is really hot. Makes life so much easier, not having to worry about heating bottles while out or in a hurry! I definitely recommend it