Got trial two weeks ago. Used it on various long/short trips. My summary: It works, but seems a bit rudimentary, especially for the price. Car tends to stay fully centered in lane, usually OK for many situations, but when large trucks approach extreme left or right in lane an experienced driver will reposition within the lane. The EAP doesn't do that, retains a center lane position. That's a bit uncomfortable for me.
Also find the EAP struggles a bit on wider winding lanes. It sometimes gets confused and doesn't initially decide if there are two lanes wide that aren't well marked, or one wide lane and it veers from side to side as it gathers more information. This is particularly noticeable when entering an exit ramp that is poorly marked.
I also dislike the constant feedback needed to keep EAP engaged. When EAP is active the system prompts you typically in two minute intervals to start. You then have to give feedback on the steering wheel, or by tapping the gear indicator down (that's a nice tip given in the forum - it mimics the same reply as gripping the wheel). The frequency of the needed EAP prompts can also increase if the system is in bad weather and can't see the lane markings clearly.
For me the result is that the EAP isn't worth the price. If I have to continually provide steering inputs/or tension on the wheel, have to engage manual driving during poorly marked sections of road, and have to be more engaged in poor visibility conditions, the EAP isn't worth it to me.
Another point - the EAP trial provides a $5500 purchase price, but you also have to pay state sales tax. That may not matter for everyone, but in NC where I live it makes a difference. Buying EAP during initial purchase applies the same tax rate as the car - which is 3% for a motor vehicle (regardless of which county you live in), but in my county the state sales tax is 7.25%. If you buy EAP during the trial the tax rate increases to the standard sales tax rate in your county. For me that means instead of a 3% sales tax if bought with the car as an initial purchase, I would now have to pay 7.25%. That makes the EAP $5,898.75 instead of $5,150 if purchased initially with the car. So the step up cost isn't $500, it's $748.75. That's not necessarily enough to stop me from buying EAP, but given my neutral opinion of EAP as it currently works, it's enough for me to not order it when the trial ends. Your state taxes may differ, but it's worth checking out before ordering the car to avoid paying extra tax after the trial.