I'm sure there are many people that are looking at this product and comparing it to the US version. Perhaps you yourself, like me, have chosen to go with the Japanese version for the sake of extra features. I will try to inform you ahead of time of what to expect from this watch that will inevitably become minor shortfalls (At least here in the States). First off, if you're getting the Japanese model because of the time-sync function please just go buy the US model. The sync occurs during the AM and is not constantly sync-ed. Another words, don't expect the watch to behave like your cell phone where the time changes immediately as you go from one place to another. If you go to another location, the time on the watch will not change (unless manually sync-ed for tuned) until the AM (which means the watch will be showing the correct time the next day). Second, the temperature, pressure, and altitude measurements are all shown ONLY in metric (Celsius, hPa, and Meters). There is no way to change this on a Japanese version (At least on this model). The US version shows in Fahrenheit, inHg, and Feet. Lastly, the owner's manual is completely in Japanese. The last point however is extremely minor as there is a English owner's manual on Casio Website. Look for the owner's manual number 3145.
If you understand and accept the above "shortfalls", you'll love this watch. Durable, easy to use, and very easy on the eyes. The first thing I noticed was the surprising lack of weight. This watch is very easy to have on. The band is very comfortable as well. The combination of the weight and band quality makes this watch one of the best "set and forget" watches around. There are many "complaints" that the readout is very dim and the back light doesn't help much. There are also complaints that the back light doesn't stay on long enough and that there is no way to change the duration of the back light. Well, I personally have not found any of the complaints to be of an issue. I can clearly see the read outs on the watch and the back light is more than sufficient. I do acknowledge that the duration of the back light is very short but I don't have an issue just pressing the light button as needed.
Overall, I find this watch to meet or exceed my expectations. I will say however that if I had to do it all again I would choose the US version. The "extra" feature on the Japanese model just don't justify the cost difference.