I think this light is a great idea and it works so it gets 5 stars - on a purely technical level it can still be improved. I would prefer to use the blinking mode on this light and then when you break it adds the solid light, however the blinking mode is an epileptic techno fit not a nice calm attention grabbing blink like some of the other PDW lights. So I don't use it, instead I have a second blinking light on my pack and I use the Gravity light in the always on mode that gets brighter when braking.
It's easy to use - it remembers what mode you were in - so when turning it on it always goes to the last mode it was in - very good UX design choice.
There are definitely times when it falsely decides i'm braking, usually when going over bumps - I'm actually happy with that since it is better than if missing detection of braking.
For brightness, I think it is the right amount. When lit up in braking mode it is very bright, I actually would not want it to be brighter.
Ive used this for a few months. No moisture or usability issues. The blink is sufficiently bright but not too obnoxious to follow. The lense helps disperse the pattern a bit to not blind other cyclists. Seems like it has to be charged about every 15 hours or so. I would buy one again.
The mount has changed from previous PDW tail lights. The old style isnt compatible which was a bummer.
The brake feature works OK. The light switches to a solid pattern pretty regularly on rough stretches of pavements (e.g. chip seal will set it off almost indefinitely). It does reliably detect harder braking.