I have a stages unit on my bike...I like it and haven't had any issues out of it. (knock on wood)

I use it every time I ride the trainer to a sufferfest video. I know my different power zones and use it to keep up with the changing pace of the workouts; this will become a bigger part of my bike "riding" over this winter.

The meter really allowed me to see how much power I can put out without blowing up on a climb...and I would say that is where it has really helped me with my biking. I'm sure other tools could do the same thing, but the power meter giving me numbers right away on my garmin that I can read with just a glance really did help me. I still look at it when hitting a climb.

It allowed me to pull the speed and cadence sensors off my bike, which are just unsightly.

I don't use the meter on every ride, but those times that I really want to follow an interval regime or some sort of training plan, the PM has helped greatly. It sort of motivates me in that regard. I remember using the PM to pace myself on this one Strava segment that I wanted to PR on...about a 10 minute flat ride. It helped keep me from blowing up early on.

I guess since using it I've gotten faster too...so there is that.