Casio has a detailed writeup about this watch and, wow! There's a lot of information here! https://www.casio.com/us/watches/gsho... . This is a GShock Square unlike any other in my collection. It features "SolarAssisted" charging to keep the battery running year after year. In theory, with enough exposure to good lighting, the watch will have plenty of power. However, it also comes with a USB charging cable for that battery, because it uses significantly more battery power than the other Squares I own. I find that I've needed to use the USB charger once or twice a week during these last few winter months.

This watch also has a Memory in Pixel or MIP display, which will give a much more pleasing look than the negative LCDs of some of my other GShocks.The MIP display also makes it possible for each mode readout to look completely different from the others. This watch does NOT have Casio's Multiband 6 or Wave Ceptor technology to keep itself synchronized to "Atomic Time" but, instead, it receives time adjustments through a Bluetooth connection with a smartphone or tablet.

If you're used to using some of the other GShock models I use, like the GWM5610 models, you might find that the operation of this watch is nonintuitive. The combination of button presses to reach the various modes and to use them is different in a way which is still a bit confusing to me.

But the really, really big difference between this and my other GShock Squares has to be that this watch has sensors on the back to track my heart rate and blood oxygen levels. And, if I take the time to lean how to REALLY use this watch and the companion "Casio Watches" smartphone app, I can do a whole bunch of fitness tracking.

Speaking of using the Casio Watches App through a Bluetooth connection, I know that some GShock fans would rather not use any Bluetooth functions and features. If that's your preference, I'll tell you straight up that you shouldn't buy this watch. All of that fitness tracking stuff is just way too cumbersome to use without the app. It would drive you crazy.

Honestly, I am not too concerned about being able to track my fitness, heart rate, etc. using a watch. I'm not really interested in having any kind of smart watch or fitness tracker. But I'm convinced that if I wanted to do that then I might find that an Apple Watch or a Garmin Watch can do those things better than this GShock can (even if they aren't as objectively tough as GShocks). And that makes me wonder if this GShock will be a successful product. Its normal price is $299, which is a bit high for a GShock Square which isn't a limited edition or made of special metals or things like that. But that MIP display is certainly impressive. Overall, I think this would be more attractive at a lower price. And I wonder if, ultimately, this watch is just a stepping stone to a more refined product that Casio might release in the future. We'll see.