Serenity Caldwell, writing for iMore, digs into the differences between the Series 3 Apple Watch and the previous Apple Watch models, as well as the differences between the GPS-only and GPS+cellular Series 3 models.

A few points that stand out:

The GPS + Cellular Series 3 has double the storage capacity: 16GB to the GPS-only’s 8GB.

And:

the GPS-only Series 3 is limited to just aluminum Sport and Nike+ casings (silver, gold, or space grey) with their Ion-X glass screen. In contrast, the GPS + Cellular Watch retains the higher-end casings formerly present with the Series 2 in addition to the aluminum Sport and Nike+ casings. This includes options like stainless steel, white and grey ceramic, and Hermès steel.

And:

All Series 3 GPS + Cellular watches have a red dot on the Digital Crown.

And the biggest point of all, on battery life while talking via the Apple Watch:

3 hours connected to iPhone, 1 hour w/ Cellular

Three hours connected via my iPhone might as well be infinity. If I’ve got my iPhone, I’m going to be talking using my iPhone. I talk via my Apple Watch very rarely, and usually for very short calls when I just can’t get to my iPhone.

One hour battery life talking on my Apple Watch without my iPhone seems extremely low. If I make a half hour call, presumably that’s half my battery gone. Gonna need a recharge.

Perhaps Apple’s marketing research shows that likely buyers want the freedom to not carry an iPhone (runners, for example), want to stay in touch, but don’t anticipate making calls on a regular basis. That would work.

Good, detailed post from Serenity. Check it out if you are thinking about moving up to the Series 3.