It’s encouraging that several express the same feeling. There are certainly choices, like font style and size and user interface design, that can make readability better, particularly compared to a much smaller or poorly designed LCD. And screen size and resolution, which for the Petrel are both high, have a big impact. But as someone who has worked on color computers for many years, using the same screens and technology as Shearwater (of whom we are big fans), I can say that readability is bright sunlight is one of the more common complaints for all color computers. I was just trying to make the OP aware that for some divers this is an issue.
That's true, and I guess it has to come down to looking with your own eyes. If we can't agree on the color of a dress on Facebook, then we won't be able to agree on the best display!
I guess if you were going to have a trade off between readability in bright sunlight and readability underwater for a dive computer, I would pick the latter. For really great sunlight readability, I think that the best is that digital ink stuff they use in Kindles, right? Don't know if that could be used in a dive computer, or if that would require battery draining illumination in any place other than a shallow tropical dive site.