Hey,
So essentially, from what I know, this ride is going to be incredible. Even for the biggest ride chickens, hear me out; don't miss it. (This goes for parents worried about their small children on the ride as well.)
(TLDR: This ride is an absolute cake walk. I compare its speed and drop height to other attractions in Disneyworld. This ride is going to be so good, please don't miss it for anything. Also, watch the movies first or you probably won't understand what's going on.)
If you did Slinky Dog, the "drop" on that was around 15 feet. From information at D23, the ride is going to have a 20-25 foot drop. That's only 5 feet taller than Slinky Dog, and around the height of a giraffe.
The drop speed for TOT (which is 131 feet at 13 stories high) is 39 miles per hour, almost half as low as Test Track. This means that, by doing 131 divided by 20 (which lets you know that the TOT drop is almost 5 times as intense as ROTR which makes ROTR look small), you can guess that the drop in ROTR will only be 15 mph. You drive faster than that in a school zone.
Motion sickness won't be that bad either; from what we know, only about half of the ride will be virtual reality and the rest will be based on a trackless ride system. For those with screen problems but are fine with general bumpy driving and vice versa, at least half of the ride will cater to your needs.
The drop isn't at all big. Twenty feet is nothing, trust me. Plus, you'll be ready. The drop is slow and short enough for you to be in the same exact (trackless, I may add) ride vehicle with no big seatbelts. From what we know so far, it'll be like putting on a car seatbelt. Don't expect any over-the-shoulder seatbelts like they give you on roller coasters; you won't be needing those. It may not even be a car seatbelt, it may just be a lap bar, which is even more low-maintenance. Same thing they give you on Splash Mountain.
Speaking of Splash Mountain, the drop height is 49 feet, almost twice the size of ROTR. Plus, the ride is moving down at around a medium speed. If Slinky Dog is 40mph and ROTR is 15mph, that's small compared to Slinky Dog. I tried to attach a piktochart I made of a graph comparing ROTR's height and speed to other rides, but it said it was spam so just DM me for it if you're still interested.
Frozen Ever After's drop height was 28 inches. ROTR is smaller than that.
If you have a small child however, I'd not worry about the ride and only worry about the action sequences. There's real lasers being fired.
Please note that, if you don't watch the new Star Wars trilogy, you'll be completely lost. Trust me, I went on Star Tours a few years ago not having seen any of the movies and I had no idea what was going on. This is an intricate, immersive experience that makes you feel like you're in the movie. You should probably see the trilogy.
Anyway this one's long (clocking in at 15 minutes), so there will be plenty of time for breathers if you're still a bit freaked out.
Nonetheless, I hope this helps. I had to be dragged onto Test Track by my sister and didn't regret a thing. If I thought TT was good, this will be better. Don't miss out!