Conrad Stoll (via Dave Verwer):

The best Apple Watch apps in my mind are the ones that include the most useful and frequently relevant complications. The watch face itself is the best piece of real estate on the watch. That’s park avenue. It’s what people will see all the time. The complications that inhabit it are the fastest way for users to launch your app. Having a great complication puts you in a prime position to have users interact frequently with your app while inherently giving them quick, timely updates at a glance. It’s an amazing feature for users, and the most rewarding should you get it right.

I don’t think that’s where Apple would like the Watch app ecosystem to be today, and it’s hard to argue against the greatness of complications when “full” apps are slow and barely usable. I also feel like I’m not too enthusiastic about Watch apps right now because (in addition to slowness) my most used iPhone apps don’t offer complications yet.

I also agree with Stoll’s last line – “when a user chooses to place your complication on their watch face that’s when you know you’ve built a great watch app”.