It is HTML5+CSS3 and for now requires JavaScript enabled for a few SMF functions I haven't obsoleted, so if you don't use a browser capable of modern web tech (aka a modern browser) don't ask.
Some pieces that have been uploaded do still need cleanup (like the breadcrumb nav), so I won't be accepting comments and suggestions until I open a thread specifically for them. My personal dev methodology for this theme is modern desktop browsers first, then smartphones, then handle stragglers like IE8 users on XP if necessary.
I'm already thinking we ought to move ALL of our desktop-written software to the web.
I understand what you mean, I worked in a web development internship for a couple years. In terms of developer-side, doing things web-based is almost entirely upside - automatic updates, so all your clients are using the most recent version, easier to find runtime bugs, all kinds of things. The only reason I'm not all for it is the realistic lack of infrastructure.
Also, I really wish people would stop using IE.Seriously, why can't they just implement the standard like everyone else does.