It's "nothing like a smartphone." Geez, does everybody who in some way doesn't want smartwatches to take off or is just Debbie Downer have to compare EVERYTHING to smartphones? Smartphones right now are such a unique category that it's insane to compare other things.
People were already moving toward only having mobile phones, and Apple took what BlackBerry had done and just blew it out of the water. It didn't happen overnight obviously since it took a year to get 3G, I think another year to get an App Store, then it really took getting to the iPhone 5 (the sixth year of the product) to hit a really mature product. The iPhone 5 had LTE, a larger display, a fairly rugged design and very good cameras. The LTE addition was really key because of how darn fast it is, faster in some areas than most of the wired connections I use.
My dad still has an iPhone 5. What REAL reason is there for him to upgrade even now? He doesn't mind the smaller screen since he uses his iPad way more. He isn't a data hog at all, so even faster LTE isn't a concern. The battery life is fine for him. He would use Touch ID, but it's not compelling enough to him for an upgrade.
So six years in Apple basically hit what I would call maturity on that product. Two years later you get the iPhone 6/6+ with Touch ID, NFC, etc. etc. that pretty much silenced all major complaints about the phone that aren't "I can't download widgets like I can with Android" or other such things.
Apple has the resources to slowly build watches up. Right now they're held back by cost, need of an iPhone 5 or above, battery life and lack of the so-called killer apps. But as the next couple of cycles go by, I'm sure we will eventually get a standalone model and perhaps work up to two or three days of battery life. There might be a sport model made for swimming. There will likely be a cheaper model at the low end -- probably just the previous model -- to make it more affordable. We have no clue what apps are going to come about, and some of these sensors rumored to be in there and that could possibly come later could make these game-changers in the health industry. I don't know how possible this is, but if this model or future models could read blood sugar and/or blood pressure accurately, it could put entire product lines out of business.