Well first, I sit down. Then, the roller coaster goes vroom vroom. Then I get off.

There are lots of roller coasters with blackout sections; at King's Island, the studio backlot coaster has roughly 10 seconds of blackout. As a sighted person, it's more intense because I can't anticipate where the train is going to go. Overall, I'm going to guess that the answer to your question is "just like you, but without being able to brace for oncoming turns".

I hate 'em. Mostly because if I'm upside down, I get sick. Doesn't matter how long, or why, or when. If you turn me upside down, I will throw up. It's a fixed law of the universe. I can spin, or go up and down, or side to side, or any other motion. But upside down means it's instantly time to toss my cookies. So my inability to see the track means it's impossible for me to judge what I can ride safely, and what I can't. And even if I tell friends about this, the first time I go on rides with them, they assume I'm not that serious. "Ah, it's not that bad. I just won't mention it." Then they're sorry!

Theyre pretty fun

They're awesome! There's the moving and the falling and the rising and the flipping and the spinning. I went on the Saw roler coaster at thorp park and it was great! Apart from the scary speakers that you walk past and they make a noise, that part wasn't fun.