Apologies for the length. 
#1.
I like the “What this shows” section, and the Current rating: summary with label. Those are very clear. I also really appreciate the context that a 92% is Above Average and how those bands are broken out. I played around with the interactive chart and really like the selection zoom.
The biggest UI issue for me (currently on laptop) - the Average (88-91%) label overlays the CHH lines. It confused me for a minute, because the current rate is Above Average, but the chart lines are right under the Average label.
It might help if each of those labels were actually inside the section they’re representing, instead of above it? Even if you bumped up just the Average label so that the lines can be seen, it still gives the impression that CHH is in the average band when it’s not, but there’s not really room below the lines / above the Below Average label.
I don’t know if making those labels transparent would help - you’d see more of the lines, but the words would still be blocking part of them?
Maybe see if those labels can be moved off the chart, although that might cause issues with width? This is the similar to #6 from @WendyFoundHerHEA
Also, without the labels, I think the color differentiation between tiers would be really hard to see, especially between Average / Above Average and Do Not Visit / Much Below Average. It’s very pretty right now, but I think there needs to be more contrast.
There is some weirdness if you use two fingers on the touchpad, in both selection zoom and panning modes (click + 1 finger drag works fine). Perhaps disable that if possible?
I might make it clearer that this is “Thumbs-up Ratings over time” in the title. I think I need to rate more restaurants in Touring Plans.
I’m used to more of a Yelp or Google reviews model where they get rated on a 5 point scale.
#2. One of the most important for me in finding this data useful is being able to recalculate that “current rating” for different time series. Is the 92% since 2010-09? Could I get a rating percentage since, say, 2022-01 instead (based on the selection zoom)?
Personally, I research restaurants based on menu and reviews. Some restaurants are amazing but don’t have menu items that look super interesting to me (e.g. Citricos), or I know someone in my party will have issues eating there.
I really want to know what dishes people liked the best, versus just having an overall number. I would love a quick list of “top dishes” or “most recommended” (although as @melcort10 noted, that can get stale pretty quickly, so it might be hard to maintain).
#3: I really like seeing the comparison lines in the sample chart. I’d love to do that with more than 2 restaurants.
I would be okay without comparing on the same graph, as long as there’s a page that has the current ratings for all the QS restaurants side by side.
Also, if I have multiple lines enabled in the chart, only the mouseover box for the leftmost line in the list shows up. I would expect that if I am mousing over the CHH line, its box shows up, but if I’m mousing over the Pecos Bill line, the PB box shows up. I can’t get the PB box to appear without turning off both CHH and CHH trend lines.
#4. Ratings over time is really important as long as you can choose your time series (like in the sample chart).
#5.
Would showing margin of error give insight into how spiky the reviews are (inconsistency)? If so, I’d definitely like to see that.
I’d also like to be able to click on the #2 of 12 / #8 of 122 and be taken to the full list (so I can see which place is #1).
If there are reviews / surveys with color, I’d like to be able to click on the 15,584 surveys to be taken to people’s comments.
#6. I guess maybe the labels of the tiers, if they can be moved to a legend or key or the like not on the chart.
#7. How do you calculate the shaded tiers (Above Average, Average, etc.) - are they consistent across all types of dining, or do they differ based on categories? Is it a flat scale or like a bell graph?
Yes! Also lounges in the same area.
Also this.