I tried out Stryd. It's going to be more precise than most (any?) GPS device. I mean precise in the sense that a route will measure close to the same distance every time you run it. The new one also supposedly measures the effects of wind (I didn't have that version so can't comment on it). It also claims to be "the most accurate" (in the sense that a distance will be measured correctly). I'm not 100% sold on that and would have liked to test it out more, but it was closer than the GPS watch I use now, especially in GPS unfriendly places like wooded trails.
I really liked the data output, and the app was pretty good. It reminded me of Garmin's app but maybe a little sleeker. There is an option to playback a run. It was kind of cool but seemed to take up a lot of processing bandwidth and not actually be that useful. I didn't have any GPS watch at the time to verify this, but I believe it will connect with most of the Garmin watches to give you a look at realtime output from the pod. They also seem to be a smaller company and have pretty good product support.
Keeping up with the device itself, the charger, and the clip for your shoe can prove challenging. Unlike a watch, which you are likely to be wearing all the time, you have to remember to have the Stryd pod with you when you head out for a run. I lost one of the two shoe clips that came with it when it fell out of my pocket at work one day (I had it in my pocket because I was running after work). The final downside for me was the cost and the lack of free return shipping if you find you don't want it inside the first 30 days.
Before trying Stryd, I ran with a basic Timex and would just guess distances of unknown routes based on feel (I was surprisingly close to the GPS/Stryd measures on most routes). Ultimately, I ended up saving myself a chunk of change and going with the Garmin 35 ($85 when I bought it, but they're regularly