I agree that it's much nicer than ERB for HTML, but I still use ERB for, e.g., config file generation.
HAML, though, shares the same fundamental problem with ERB: it's straddling the code/template fence. I wrote the Hoshi ( http://github.com/pete/hoshi ) gem to address this, and used it in the last Rails application I wrote (still in production), and still use it for HTML when I need that. (It's still in the "personal itch" phase, so it's only maintained when I notice that W3C doesn't like something or when I'm missing a feature. For example, I haven't done any HTML5, so I haven't put any in.)
For anything requiring a wall of text (in HAML, ERB, Hoshi, whatever), I think it's a mistake to put it into your view code. Make a place where copy goes, decide on a markdown format, and write a helper that pulls in and processes that text. Even if the coders are writing the copy, it's helpful to have the text seperate, and easier to edit besides. And if it turns out that you need the text editable via a web UI or something, it makes the change easier: modify the helper to fetch text by name from the database rather than the filesystem, and import all of the text into the database. Everything is easier all around; I'm at the point where it looks like a code smell when I see walls of text (or frequently edited text) in a template.