I am interested. I'm already in the Apple ecosystem. One of my biggest annoyances in daily life is needing to fish out my phone every few minutes because of alerts (I know, first world problems) on buses and subways, even just walking down the streets. About half are things I need to deal with right away. A glance at my wrist to tell me if this is something I need to act on right away. I understand that other smart watches can do this but for me, Apple integration is a feature. If it truly lasts all day, I have no issue with charging while I sleep. Siri works pretty well for me and I'm curious how easy it will be to just speak an answer. I may try one of the cheaper models or perhaps wait f0r the next generation.
When the first iPhone came out, it didn't even have apps and most people saw no need for it and thought it was a terrible idea and would never sell much. When the iPad debuted, it was also considered ridiculous and 'just a big iPhone'. The watch may be not much now, but the future may be bright. Just the health diagnostics alone are very, very interesting.
I used to use a phone for only phone calls, now phone calls are one the least important things I do on my phone. Right now, I use my watch for only telling time (and as a piece of jewellery) but this too may change.
I watched the announcement and it started with the opening of a store in Hangzhou, China. In the last quarter, almost 2/3 of Apple's profit came from outside of the United States. I believe they are moving their focus from a fairly saturated western market to the global community. Some of the use case scenarios for products may make perfect sense in, say here in China, but not be very appealing to the western market.
The watches will sell well here. Those stupid drawing on the face and heartbeat sharing functions will be massive here, and not just with the young.