I’m no pro runner, but I did want a running watch that had some very specific features. Pacer Pro ticked off my entire list and then some. I’ve been running with this device for about a month now. Paired w a Polar chest strap monitor (not necessary, but I already had an H10 so I just use them together), PP delivers enough feedback and after-workout metrics to really satisfy most every runner. Polar Flow, both in app form and on the web, is a worthy complement to the device. That’s the good. There’s one really big not-so-good. The device just randomly stops working. Sometimes when I’m wired recharging/syncing (and don’t get me started w Bluetooth syncing on iOS, which is a nightmare), the device screen just goes…dead. On awaking this morning, the device screen was…dead. I had to wire it to my laptop, wherein I was instructed to set it up again as if it was a brand new device (fortunately, the Flow web app retained all my previous workout data), and start my sleep tacking all over again. It is a frustrating and not entirely unnerving habit, not knowing whether it will just stop during a critical workout. So, I can’t give this 5 stars for this reason alone. Don’t know if Polar needs to do a firmware update or if I got a bad model, but whatever the reason, it isn’t something I’d HIGHLY recommend. When it works, it’s a great tool. When it doesn’t, it’s a source is genuine frustration. UPDATE: Forget what I wrote about the chest strap being unnecessary. My personal experiments w using the PPP w and w/out the strap indicate that if you want accurate HR numbers, you’ll pair it w the strap. For example, last night it failed to record my night’s sleep completely despite the fact that I wore it (tightly, as Polar advises), and then on a completely casual walk on my rest day, it recorded HR zones from the low 60s (which I would expect), to 145 and above, which is my red zone which I can only reach w a full-on sprint. So now, this device by itself is not reliable AFAIC, at least when it comes to accurate HRs. Pair it w a strap, and it makes a fine running buddy. Alone, not so much.