Liked this comment from another Brit (note the implicit fanboi dig)
I think if you look at how it is being marketed, you'll see that Apple are targeting up-market, fashion conscious, watch buyers for whom I suspect the features are secondary to the style and image of the thing, so women. At the same time they are offering men more butch versions with gadgetry included. The chaps with expensive cars who buy Swiss mechanical right now. This is additional to twenty million Americans who buy anything new the company produces.
If they pull it off, they'll have done rather well.
As for how long the battery lasts if someone overdoes the geekery, well how strong is the competition?