Comparing this to the 25yr old controller it replaced, it's sleeker, easier to program, the history and stats the app provides, and being able to control it from an app makes this a no-brainer purchase.
First the install - super simple. Label wires and take pictures of everything before you yank the old controller. Because many old controllers the wires wrap around a screw terminal (so the stripped wire is bent and longer than you'll need for the Rachio), simply cut the wires just below the where the lead insulation starts (leave enough behind to see the wire color). That way if (when) a label falls off, you can look at the old controller and match where that color wire was connected. Strip the wires a 1/4" or so, easy push to connect.
When I compare to what I was expecting it to be able to do, some of it fails short, but every issue is software related, and it appears some of my main concerns may be fixed hopefully in the next couple quarters.
My primary purpose (justification) was to be able to fix/adjust sprinkler/drip line heads in the yard using Siri to turn on and off zones as needed. Almost a year later I've not achieved that. While the Rachio HomeKit connection worked the first time I set it up, after about month it stopped responding in the Home app, and after deleting the item from the Home app attempts to add it consistently fail. Chatting with Rachio support (last time in August 2021), they were aware 'some' units weren't connecting, but they had new firmware they were about to beta that implemented the HomeKit ADK directly, and once that was done and tested they'd update the WiFi firmware and retest everything, and roll that out. As of December I'm still limited to protecting my phone from getting wet and turning zones on manually through the app. A bit disappointed, but that's still way better than running back-n-forth to the garage to turn zones on and off.
The second goal I hoped to accomplish was saving water/lowering my bill. That I have accomplished, though not as much through the 'intelligence' of the software as I expected. Most of the savings has been it using local forecast and deciding not to run because rain appeared likely soon. That's works most of the time, but I still find I have to manually override it's decision to run or not some of the time - fortunately it's all done in the app, so it's a useful feature.
Yes, it can automatically adjust the watering time per zone depending on season and adjust for past/predicted weather, but it makes a couple assumptions that prevent me from using much of what I thought would be killer features. The smartest schedule mode assumes it can adjust when (what days) to apply water. I live in an area almost always under water restrictions - so for the main yard zones I have 1 day and only certain hours within that I'm suppose to water - the software can't deal with that. The other intelligent mode adjust the time per zone based on the season, but there is little to no tweaking/settings you can control for that, it just picks a new monthly value on blackbox logic, so you really have to examine the adjustments it makes monthly. Instead of a fantastic advantage, my old controller was actually better at this. While it didn't have a clue of impending rain, adjusting the watering times for season was incredibly easy (though manual) with a global 'budget' value I'd tweak monthly from 40% in the winter to 150% in the summer.
The most unexpected limitation in the software I discovered is with 2 of my 11 zones which are drip zones. The software's logic and inputs don't get that these run for very brief times, sometimes multiple times per day. Multiple times per day you can manually create by creating multiple schedules, but it only supports watering intervals rounded in minutes. So 2 minutes or 3, 3 or 4, but not 150 or 210 seconds.
Other useful features I didn't expect is an option that overlaps starting and stopping zones - so instead of closing a zone and then starting the next, it can do that in reverse: start the next zone and close the previous, which results in a softer/quieter operation on the whole system.
Overall great addition. Would be a full five stars if the 'intelligence' could better deal with water restrictions, watering times could deal with fractions of a minute, and HomeKit actually worked.