I find them extremely useful for what they are. Moreover, Nightstar has consistently increased the brightness with new models. I posted a "review" of one of their latest models a while ago. It's probably in the archives.
I have 4 nitestar flashlights. The first two were before they upgraded the LED. Maybe a DS but no expert on 5mm LEDs. The other two with the newer (maybe older now) LED. A large and CS for both. Guessing if I seen the newest green CS as stated in the review for 20 bucks I would bite. Only pack the CS in my BOB with a headlamps and flashlight just incase the world ends. Anyways they do work but have not used them for anything. Maybe the very low light and larger size of even the smaller CS has something to do with that.