One thing that bothered me when testing Dotty was that I opened a file with vim and indented with a tab. That file had been created with spaces for all indentation. Even though my file used the old syntax and had braces for everything, this still threw an error. So whitespace is now significant in Scala 3, even when you are using a syntax where it shouldn't be. I worry this is going to cause a lot of headaches for students because whitespace isn't normally visible and it will be challenging for them to figure out why things aren't working when everything looks fine.