And even with the stuff it can handle, the poor 4S gets winded pretty quickly. Ars points out that the phone's guts offer about a quarter of the performance of the iPhone 5S, and an even smaller fraction compared to the newest iPhone 6. Apps launch more slowly—sometimes taking 50 percent longer to load—with herky-jerky transitions that hang and hesitate.
All of which is kind of secondary to the main problem: The 4S was the last of Apple's phones with a 3.5-inch screen. That size was once considered the golden rectangle of smartphones. But everything is bigger in the future, including iPhones, and the added rows of buttons and bars that appear in iOS 8 eat up valuable screen real estate on the great-granddaddy iPhone.
So yes, it's entirely possible for you to download the brand new iOS on your brand-old iPhone. And by doing so you'll get a lot of goodies like more keyboard options (finally) and fun widgets. It's a trade-off you might be willing to make—Ars Technica thinks so.
But to us, cramming that shiny new software into the 4S's cozy yet slightly musty house is a tight fit that will leave phone and user alike groaning. New features like widgets and alternate keyboards are nice, but not at the cost of so much screen space and speed.
Have some pity on the old warhorse, and let it stay pleasantly outdated, for its sanity and your own. At least, until iOS 8.1 hopefully takes older devices into account. [Ars Technica]