If by "consistency" you mean "function over form" then sure. It's basically brutalist.

If a website's aesthetics were important to Facebook's users they never would have joined. http://www.businessinsider.com/what-facebook-used-to-look-li...

Like Craigslist, people don't really have a choice with Facebook. You either use it, as ugly as it is, or don't.

I'm not sure what you mean. You mean they don't have a choice in the design? Because there were plenty of alternatives (MySpace). Facebook just provided a better experience.

Facebook's software might be better, their uptake was better, but that doesn't mean their site is more visually appealing. It just means it's more effective.

Function over form.

By "consistency" I mean that its design is evolutionary and hasn't radically changed since the beginning.

http://time.com/11740/facebook-10-year-anniversary-interface...