Expecting delivery in the next week or two, waiting back for that call after telling them when delivery would work best for us, and I know for a fact the one thing I am going to miss is the cargo space and the lift gate. Test drove the Model 3 a few weeks back, thought it drove and felt great and it drives "like a Tesla" so no real difference there, but when I checked out the trunk space it really hit home the difference. Where as I could stand and put anything almost into the cargo area of our Model S and easily reach anything in there, the opening due to it not being a hatchback on the Model 3 is so much more shorter, I'll probably be bending lower to reach things inside, and boxes and such I could have fit in the Model S won't go in the Model 3. Big boxes aren't going to necessarily fit in the rear door area to the cabin either.
I'm not a fan of the screen placement, would rather it been vertical like on the Model S. I find sitting in the passenger side it kind of sticks out where you could hit it with your knee if you are a long legged person and depending on how you sit. Not an issue on the driver's side as you encounter the wheel first. I can see where in that early accident the passenger hit the screen and got cut. Having gone vertical would have made that a non-issue. Did notice a lot of glare on the screen when I did my test drive, more so than on our Model S since the screen is more recessed and I don't think the windshield goes back as far on it as on the Model 3. But really think the biggest thing I'll notice is the cargo space. Hope to find out soon! We'll have both cars so can always take the Model S when we need the extra space but for someone who will only have one car I would say that is the biggest adjustment in going from a Model S to a Model 3.
And BTW really wanted to get my old car replaced soon and wanted another Model S. If Tesla had come out with a refreshed Model S with new battery tech, we might have ordered one and kept our Model S as our second car instead of the Model 3. Just didn't make sense to spend the extra money on an MS right now, with our circumstances. The perforated seats might be back on the refresh and I really had wanted a sunroof in my car too so worse case we trade in the Model 3 down the road. Not sure if those options will ever get offered on the Model 3 in the near future or ever. But I will add we love our Tesla and expect any car/s in our near future beyond this Model 3 purchase will be a Tesla as well.