I've been using Comma 3/ Open Pilot on my 2021 Palisade for about a month.
Some thoughts....
Installation - you don't need to be a mechanic, tech wizard, or super handy for the hardware install but might be difficult for someone with two left hands. There are several install videos available. Removing the mirror trim is fairly simple and there's ample space to stock the splitter. Running the cable behind the headliner is easy and can be done with your fingers (even my fat fingers). The side trim is a bit more difficult but I had no issue using a metal credit card (thanks DD) instead of a trim puller.
Downloading the basic open pilot software is simple. Simply enter the URL and press install. Be careful installing forks. Make sure to read all the data. Installing non compatible forks , such as forks for a Comma 2, can brick your device. (Can be repaired by flashing the device). I'm currently using one of the sunnypilot forks, more on that later.
As far as the difference between openpilot and the vehicles stock ADAS, that obviously depends on the vehicle and any forks installed.
I chose my new vehicle based on my frequent rentals. The choice came down to price, comfort, reliability, and track record but also the cars stock ADAS. Based solely on the stock ADAS, I would have bought a BMW, Caddilac, or Ford with Blue (super) Cruise, available standard on F series trucks, Expedition and other models. (Jeeps has some pretty good SUVs but the stock ADAS is trash in my opinion and not very compatible with openpilot- if this matters to you, check the open pilot website for at least explaining the levels of compatibility)
As another user explained it very succinctly, with the cars stock ADAS the car assists you in driving. With openpilot, you assist the car in driving.
Adding navigation either through a Comma connect subscription ($9.99 monthly) or with a free mapbox account (only available with some forks - not stock OpenPilot) is crucial.
You will need some sort of internet connection either with a SIM card and premium Comma connect subscription or hot spot from your phone.
After playing around with experimental mode and some of the other toggle features, I'm at a point the the car drive it self on highways including changing lanes (you still need to turn on your signal unless it's getting ready for an exit and then it will usually change lanes it self.) , taking most exits, stop and go traffic etc. while the stock ADAS mostly relies on sensors and radar to slow/stop the vehicle, sunnypilot has an option for visual braking (based on the e path it's plotting) and even map based braking. It will automatically slow down for curves based on the map and cameras.
Another point regarding it's limitations. It won't mimic your aggressive driving even when set for “aggressive” (yes, there is an option for that)
It does recognize many (most?) stop signs and traffic lights but it's far from foolproof. For instance if traffic light or stop sign is around a bend , it likely won't stop. There are also random stop signs that, for whatever reason, it doesn't see. I've seen a significant difference between highway, suburban road driving and tight city driving. It definitely isn’t cut out for city driving.
Is it worth it? If you do significant highway driving, especially long distance, definitely. Driver tension is gone once you get used to trusting it. You arrive completely different. Just make sure not to verify rely on it.
We really enjoy the Palisade and this makes long drives significantly easier.
We still have a 2013 Sienna but have chosen to use this for recent family trips. Obviously cargo space is an issue which we solved with a 500lb capacity folding cargo hitch basket well as a roof basket. (It also has a tow package if we ever wanted to use it)