Some watch shots

I haven't paid close enough attention to that function, yet, to really say definitively. I used it for one run and, from what I've seen on gym equipment, it seemed like the HR range was pretty accurate. The resting rate is pretty spot on, for sure. You can also set up alarms based on your desired HR range, etc so you know if you're outside your preferred range.

An Apple Watch definitely is not going to be durable for mountain biking. One spill or drop and that thing is probably toast.

Also, there are probably other fitness watches that do the same as this, maybe more, and maybe for a little cheaper. But they aren't going to be as cool looking and won't be a G Shock.

3 or 4 years late to the party, but I finally picked up a Moonswatch (Mission On Earth variant, which is supposed to be a play on the northern lights). Swatch makes it a pain in the ass to actually buy these as they're almost exclusively limited to Swatch stores and the nearest to the Seattle area is Vancouver, BC. Some color for the summer and the fake aventurine dial actually has some sparkle under light and does a decent job of looking like a starry night. I put an aftermarket strap on it as the factory velcro piece is awful.

Here's an article which goes further in-depth on this watch.