What I loved about Prototype (apart from changing my opinion about Javascript) was that it sort of extended the language itself, and made more possible with less. But now, I feel coffeescript is a better way to go. What I hated about Prototype was performance. And jQuery is way better there. This seems to be like Firefox v/s Webkit. Prototype 2.0 is going to fix a lot of things (by not extending the DOM), but that ap…
One thing that we're trying to maintain with CoffeeScript is that the generated code is just as performant as you would have written in raw JS -- i.e. loops are just loops. It would be lovely if that sort of performance were possible in a JavaScript library that supplied "each", but sadly, it's not.
Seeing CoffeeScript is the first time I've felt I can write a full app in Javascript. You and your team have produced something truly significant.