Headline get your attention? Good. Because I'm about to go honey badger on the devil's incarnation that is "Responsive Web Design" and tell you why it is bad for your web site and for the future of UX in general.
RWD has its merits: Optimize for the form factor, widest net in terms of audience reach, ability to adapt and adopt new and ever-changing technologies.
But the most important benefit to RWD is for web designers and developers: RWD lets them charge more money to create more web sites so they can stay in business.
There. I said it. Honey badger don't care.
Thanks to the magic of RWD, your current web site is not enough. You need a mobile phone web site. You will (soon) need a large-screen web site. And if the web dev really needs the cash, they'll talk you into a tablet-optimized web site as well. And a game console version just to make things fun.
Those multiple web sites need custom HTML and CSS, all in the name of making great "user experiences" for your visitors. Because if you don't, your web site will suck on a __(insert platform here)__.
Lets assume that your web dev + design team has the skills and manpower to actually optimize each platform to its best. And that they'll actually bother to really think about the UX rather than just plug in some common-code synthesizer that spits out a cookie-cutter mobile site.
But hey, you're reusing the same code. Mostly. Right? I'm achieving synergy! It's all about UX! And optimization! And these neat tools that detect user agents and screen sizes! I'm so clever.
And so wrong. Because for all the things you've gained with RWD, it doesn't compare to the one UX principle you lost. The most important principle of all.