I'm a Watch owner. The Watch doesn't need to be any thinner. It needs to be faster with more HealthKit tie-ins other than movement and heartbeat.
It needs to be a LOT of things, but the LAST thing it needs to be is thinner.
I'm not a Watch owner, and it would have to be thinner before I'd consider it. But, more importantly, it has to actually do something of use to me. And, then based on what folks are saying here, seems like it needs to be faster, have longer battery life, etc.
IMO, it as to do more when untethered from the phone. If it had GPS, that might be useful when out hiking or biking to track distance, speed, etc. Or, if it were a good independent music/podcast player, that might have some use. But, as just a sidekick to a phone, I can just use the phone. Unless, of course, I wanted a watch anyway, which I really don't.
I'm a gadget geek, and have owned a heck of a lot of Apple products. This is one of the few that I don't even really want yet.... at pretty much any price.