Functionally alcohol stoves work great in the cold...they just need a bit more priming to get going. I've used mine in weather as cold as -25 or colder and it's always lit. My tests have shown my Vargo to run longer in the cold than at room temperature.

Practically they're not as good as the competition and get a bad rap simply because their heat output is so much lower. If you don't expect much out of one, they get most jobs done just fine. They won't boil much water, won't melt snow worth a damn, and won't run as long as other types of stoves. I'm generally only using it to thaw out some food and have a hot beverage.