Star Tours was considered an E when it first opened. It was a massive hit; the line went half way down Main Street that summer. These days, I‘d say it’s a D.
My personal feeling about MMRR (based on riding the WDW version) is that, while It was quite fun, it didn’t leave me ”wowed“ or greatly impressed. It’s mostly projections, but it’s not thrilling and breathtaking like Soarin’. It’s gentle, cute, and, despite the building size, rather short. I think the trackless vehicles hinder the ride’s design more than they add anything, resulting in a massive feeling of wasted spaces and a very real problem: if your car is the first or last in line to enter or leave a scene, you genuinely miss out on content other riders are getting. I think it’s one of the worst ride design flaws in Imagineering history, and I realy hope they‘ve addressed that for DL’s version.
Again, it’s a really fun ride. But Roger, right next door at DL, is more fun and takes up a fraction of the space by using the space brilliantly.