As someone that is trying really hard to like homekit, I can understand the frustration that name99 and others have expressed.
Take my setup for instance. Ecobee3 with 7 external temperature/motion sensors, Philips Hue hub / 3 multi color bulbs, Lutron Caseta Hub with 5 remote and wired dimmers and 6 pico switches, 2 iDevice switches with power monitoring, and 2 iHome switches.
I bought the Ecobee3 home kit model last summer, set up all of the parameters for my heat pump, then paired it to homekit using the Ecobee app. Right away the Eve app showed temperature and motion in all rooms. All is well.
Added the iHome switches at Christmas time for trees and outdoor etc. Named them and paired them to homekit using the iHome app. Instead of 'Christmas Tree' and 'Christmas Outside Lights' that shows in the iHome app, the Eve app shows them as 'home switch xxxxx' and 'home switch yyyyy'. I renamed them in Eve, and it 'seems' to work fine.
A few days later I run across the iDevice switches at Lowes, which have a night light and energy monitoring. Pick up two and go through the procedure of replacing the 'Christmas Outside Lights' iHome switch with the iDevices switch (so I can monitor how much the lights are costing me to run). Knowing that homekit isn't going to allow two switches named the same, I removed the iHome switch first using the iHome app. The iDevices app fails to pair the switch (this part turned out later to be flaky firmware that resolved after an update), but eventually I get to the part of naming the switch 'Christmas Outside Lights' and get a 'This name already used' error. So even though the previous switch is removed from the system with iHome app, and it doesn't show in the Eve app, something is hanging onto the old switch name. Did it happen when i renamed the switch in Eve? Who knows, but I don't have time to mess with it so I named the iDevices switch 'Holiday Lights Outside'
With the holidays over, I move the 'Holiday Lights Outside' switch to the Garage to monitor the battery maintainer on my S2000. 'Holiday Lights Outside' doesn't make sense anymore, so I rename it 'Garage Switch'. Or at least I try to because again I get a 'name already used' error. So now I'm stuck. I don't have any switches or rooms labeled Garage...
Could it be that the 'Garage' ecobee sensor is causing the issue? I went into the Ecobee menu (on the thermostat) and renamed it 'Workshop' and suddenly I can add the Garage Switch name. So now this doesn't make sense because it is one room, why should i have it named twice. What happens if I add other devices, then what do I call them? Oddly, The other iHome switch was moved to my office for the desk light. It's called 'brucewayne's office light' and the ecobee sensor is named 'brucewaynes Office', so why didn't I have a similar conflict? Again, I don't have time to mess with it, so I leave it as is.
My wife has long complained about the single light switch in the bedroom so after investigating a few options, I pulled the trigger on some Lutron Casetas. This required a hub to link with homekit, and I sprung for the pro model so I could also control it with roomieremote (now called Simple Control). This setup without issue and all seemed well.
I figured, while I'm on the homekit train, lets try out the Philips Hue system. Another hub on the router and i have nice pretty colorful lights in my Family Room and bedroom nightlight. Individually it works well.
So here I have another 'hole' in functionality. The caseta system uses small remotes called Pico which can be mounted to the wall or nightstand or whatever and paired to the inwalll/onwall dimmer switches to provide another point of control. Except since the switch pairs to the lutron hub, it has no way to 'communicate' to do anything else, for instance, allow the favorite button to dim the caseta lights to a certain level and turn on the hue bedroom nightlight. Now you say, why should I expect it to since its a closed system that communicates with homekit? And you would be right, I shouldn't. Except that Simple Control Sync app can monitor the caseta system for pico button presses, then run a macro to control the philips hue bulbs (which are also controlled independently of homekit by Simple Control) !! If there was one app that truly tied HomeKit together it would be so simple!
So in order to do something simple, like have a button on the wall set a scene between lights from 2 manufacturers, I have at least 4 points of possible failure (Hue hub, caseta hub, router, simple sync running 24/7 on my mac) . So far it has been reliable but if I have a problem where do I start troubleshooting?
This was working well for a week before I decided that I would redo the whole thing to alleviate the room labeling issue. I decided that if I use the Eve app to setup rooms first, I won't run into the issue of conflicts. By the way i downloaded the $15 Home app which has more flexibility, but really didn't solve any of my issues.
So i unpaired everything from each app. I deleted the apps from all of my iPads and iPhones. as a precaution I reset all 3 of my AppleTV3s (because who knows which one was linked to Home kit, one of them, all of them?). I left the ATV4s alone because I wasn't going to redownload all of those apps. I used mac filtering on my router to force the switches and hubs to specific IPs so I could keep track of them (and also help with issues in Simple Control). Then I used the Eve app to setup rooms first, then added the thermostat and caseta and hue hubs. I named the sensors in the other rooms 'Garage Sensor' 'Bedroom Sensor' etc to hopefully avoid future conflicts.
Next up the iHome and iDevice switches. Plugged them in, started to pair, oh crap, i need to aim the camera (or type in the number for each one). Where is the number? on the back side of the plug! So rather than start the pairing over again, down to the basement to open the slowly filling storage tub called 'HomeKit accessories' to find the boxes that they came in, so i could pull the sheet of paper out, so i could scan the damn number!
So... I have everything more or less working in harmony. Except now, what app do I use to control all this? The Eve app doesn't show power usage statistics from the iDevice switches. The iDevice app doesn't show temperature from the Ecobee sensors. iHome app doesn't really like anything but its own switches. The Home app shows many blank 'Custom' values, is illogically laid out, and has cryptic messages like 'The hive is humming along' (???). The Lutron and Hue apps only control their own devices. Siri works, as long as you get the syntax in the exact order. And I have my phone on me. And/or my watch is within range of my phone.
I don't dislike homekit, but as name99 said, it is as if Apple didn't actually test all these products together in a real life scenario. Especially the need to scan a number that at that point in the pairing process is hidden between the switch and the wall. You could say that I made it more complicated by renaming and repurposing switches, but wouldn't I run into the same issue if the switch failed and had to be replaced? Do I feel confident that I could go on a business trip and my wife could figure out all of the above if there was a problem? It’s one thing if a flappy birds app doesn’t load on her iPhone and quite another if the bedroom lights keep turning off because Siri is getting confused.
75% of the issues and conflicts could be resolved by Apple creating a HomeKit app in the same vein as the HealthKit app. 15% could be resolved by making the Apple TV a full homekit hub that can communicate directly with the caseta dimmers switches and hue lights (the $49 Wink and Staples hubs can do this) instead of requiring individual homekit compatible hubs for each product. The other 10% could be solved if the companies that made this stuff had a larger lineup of products so we wouldn't need as many hubs. For instance, Lutron has many other lines of products that more or less could be added to the caseta system with minor changes (radio RA and Maestro use similar control technologies). But even though Caseta has been out for years, they have no plans to add a fan control. If you want to buy some $800 motorized window shades they have you covered though.
I have purchased every generation of Apple TV since the beginning and I have been stuck with this hobby of Apple’s because I’m already way too deep in the Apple ecosystem. Simple things like waiting 8 years to release an app store, releasing the ATV4 without standard apps like podcasts and keyboard support, or even compatibility with Apple’s own remote app that the 3 previous generations work with is telling me that Apple is just playing around while they work on cars or VR headsets or designer watchbands or whatever.
My main concern is that Apple is just going to let this project stall and I’m going to have a house full of stuff that will still work individually but with nothing to tie it together.
Anyway, thats quite a lot more than i expected to write and it's late so hopefully I was coherent. If anyone has questions about the homekit products above let me know and I’ll try to help.