Greg trains athletes and he's not a fan of the heart rate monitor of the Apple Watch. Leo says that nothing is going to beat a breast strap that monitors heart rate. But in time, maybe. The Watch is close accuracy wise, but it's not going to replace a Garmin for more serious, higher performance activity. His best bet is patience at this point. It's early days still. Give it time and it'll not only be more accurate, but it will have more features. Polar straps are supported by the Apple watch via Health Kit, however.
The Apple Watch will work with the iPhone 5, iPhone 5S, and the iPhone 6 and 6 Plus. He won't be able to use Apple Pay with the Apple Watch if he doesn't have an iPhone 6 or 6 Plus, however. So he may want to get the new iPhone 6 for that. We don't know yet if this will be such a great watch, though, anyone who's saying that is just guessing.
According to the New York Times Bits Blog, Apple Executives met with the Food and Drug Administration to talk about mobile medical apps. The FDA publishes its calendar, and the week of December 9th they met with people from Apple including Bud Tribble, who was one of the Macintosh engineers.