<i>A lot of IDEs/text editors can autocomplete HTML closing tags</i> was my initial response to HAML. I was dragged into using HAML, and I'm glad/frustrated for it. Glad, because by the time I finished that project I realized how much faster/easier it made things; frustrated, because the following day I started another (rather large) job in which HAML wasn't an option. It's hard to put into words why I found HAML superior to HTML. A really poor way of explaining it is <a href="http://en.wikipedia.org/wiki/I_know_it_when_I_see_it" rel="nofollow">http://en.wikipedia.org/wiki/I_know_it_when_I_see_it</a> - just replace see with do.<p>As for SASS, maybe I'll feel the same way after I jump in, but the idea of adding a layer of abstraction to CSS seems like trouble - IE 6/7/8 is trouble enough.