I keep two ambers in each of my three emergency bags (1 for each of two cars and one for the house). We recently had a power outage and they served well. I've tested the strobing functions as markers, but not used them in an actual situation.

The amount of light is enough to work/read by inside and they are highly visible outside when stobing. They claim a very long battery life, using small 12V alkaline batteries (a little obsucre, but my local drugstore had them when I checked). But I've not used them long enough to verify the claims.

The interface for changing the strobe/brightness isn't very good. You twist a split ring in a 5 sec on, on-off to increment, and then 5+ seconds on to set pattern. But I got the hang of it with some practice. However, I had to keep the directions with the lights in the emergency bags because anyone but me will be baffled.