I'm very skeptical about this product as well. It's certainly interesting, and has some appeal, but a lot of draw backs as well that have already been mentioned.
I don't think it's fair to compare the negativity to those who said the iPad would fail. I've been an Apple fan for many years and have been very excited about all their products. The iPhone was obviously the big one, largely because of the brilliant multi-touch implementation, and just the general feeling of "wow, this IS the future!". The iPad's appeal then, was obvious, as a large format touch screen offered tons of possibilities. I never doubted its success - I was genuinely shocked at the negativity after that announcement. This doesn't feel the same.
The Watch lacks such clear appeal and potential as the iPad. There are aspects that are cool, but again, those downsides. Notably it requires an iPhone 5 or 6 for most of its functions. The screen is necessarily small, but that limits its capabilities substantially. This is also, at least, one reason it makes some sense to tether it to a phone, but definitely limits the possibilities of what the Watch can be used for. The format itself is inherently limited. And for a device that mostly functions as an accessory, the high cost is problematic - it literally costs as much as a smartphone. I get that compared to normal watches it's not so bad - but normal watches aren't really popular these days.
The upsides are, basically you can do smartphone things without getting out your smartphone, kind of a controller for your phone. And fitness/health stuff. Call me crazy, but the fitness/health stuff is still pretty limited. I'm pretty into fitness and know others who are as well, and I don't think those features are substantial or useful enough to justify the cost to any fitness enthusiast. I'm an active dude and tracking how much time I spent standing, walking, or whatever just isn't useful. I already know I'm active enough, and besides tracking some cardio stuff, which tons of cheaper products already do, it offers little. The fitness stuff seems targeted squarely to those who aren't really into fitness.
So I don't know, this one is a wait and see for me. I think future product revisions will improve this quite a bit, but even then I don't know if it will ever be something I actually use a lot. With phones become thinner, lighter, and more capable every year, it seems more burdensome and unnecessary to have an accessory like the Watch. The sensors have potential, but are too bare bones ATM, in my opinion. It certainly is attractive, however, and they did a pretty good job with the various apps.
I still think Glass like devices are going to be the most successful wearable technology.