Crappy cafe / airport Wi-Fi? .... Mobile sites can be your friend...
I travel for work and so have the pleasure of crappy cafe and airport 'quality' Wi-Fi where pages from Facebook to the BBC never finish loading. Mobile sites are simpler when implemented well and can save you from all the eyeball-information-overload of the regular desktop versions. For instance, look at how bloated and overloaded these desktop sites are: Yahoo.com, IMDB.com, BBC.com or RTE.ie.... The reason I like mobile overall is that when its done well, It cuts to the heart of the content and gets away from all the 3rd party bloat that's added to make money. It is of course a PITA when you're dropped in or out of the mobile site back to the desktop due to a broken link...
In general I like sites that can run fine without JavaScript / Ajax / Java / Flash. I run Firefox with all add-ons, scripts and images initially blocked. Then I only turn back on what I need. There are so many ads designed to rob your eyeballs and so little time in the day that I find its a faster way to work. Also speaking security wise, for far too long we have permitted blending of code and content, and this just leaves so many many attack vectors open...
In summary, Mobile runs faster than the equivalent bloated desktop version. In addition desktop on a mobile can lead to endless scrolling because of page size. Overall, there's less Ads on mobile because they can't fit them. Finally, if you're roaming overseas or not on an unlimited data plan domestically, the last thing you want is a legion of ads being loaded up....