My expectation is that there won’t really be a HomeKit system with enough pieces to be worth evaluating until the summer of 2016. I do expect to use it for some things then. There are just very few devices that work with it right now.
The new Phillips hue HomeKit bridge is interesting, and I probably will buy one in the next month or two. The HomeKit/Apple Watch integration is much better with the watchOS 2.0 release, and I can imagine situations when voice control of some of my lights from the watch could be useful.
I love the echo, and use it all the time, but the watch would give me more options. And I always like options. 
But I’m not rushing out to buy any HomeKit gear right now. I’ll wait until there are more options to choose from, and more reviews about how everything is working, including geopresence.
I struggled with Geopresence for about eight months. Very difficult to get it right at my house. It’s one of those things it works great for some people, and not at all for others, just depending on local issues, including where the nearest cell tower is.
Ultimately I did get a very reliable system, but I mixed in some I beacons to do that. And it was still a trial and error set up process to get the ranges right.
If you interested in any of that, the following topic (this is a clickable link) describes my set up: