I own and have used a number of Krills over recent years and found them reliable. I think it is important to note that they are really 'glow' sticks and as such are restricted in their effective use to providing a safe, highly efficient low glow.
The only downside I have found is that their circuitry will affect radio reception if placed near a receiver. I don't know if they affect GPS receiver or electronic compass operation, or other electronics operations. I need to check with Krill on this...