It's hard to overestimate Jobs' influence on the world; the timeline of his life is liberally scattered with world-changing achievements. The Apple II helped popularise home computing, and was responsible for a lot of people learning to program. The Mac popularised graphical interfaces. (It was neither the first GUI—that was Xerox PARC's Alto prototype—nor the most popular one—that was Microsoft's Windows, which to no small extent imitated the Mac—though it was the one which popularised the concept.)
After Jobs was ousted from Apple, his next project, NeXT, was daring and beautiful, though commercially unsuccessful; however, Sir Tim Berners-Lee did create what became the World-Wide Web on one. Years later, Apple's reinvigorated Macintosh line, infused with the technical DNA of NeXT, helped to break Microsoft's stranglehold over computer standards and the leaden years of stagnation that had ensued. Meanwhile, the iPod—also not the first MP3 player by a long shot—displaced the Sony Walkman as the iconic personal audio player, and iTunes forced the hand of the recording industry. The iPhone, meanwhile, transformed mobile phones, both in industrial design (one only has to compare early Android prototypes, with their square screens and BlackBerry-esque QWERTY keypads, to the plethora of touchscreen phones which followed) and the degree of control phone carriers had over phones (which, before the iPhone, were routinely locked down to do only what the carrier saw as profitable to let its users do) and the availability of mobile internet access (which, once again, followed a walled-garden model, preserving the carrier oligopolists' profits, again at the price of stagnation). Then came along the iPad, succeeding spectacularly where tablet-shaped computers had failed for decades. And, outside of that, Jobs helmed Pixar, which produced computer-animated feature films which were not only massively popular and technologically innovative but critically acclaimed. It beggars belief to think of one human being as having had that much impact on the world, over and over again; had he had a few more decades of life, there would doubtlessly have been more.
WIRED has a list of tributes to Jobs from various luminaries, as well as an eulogy by Steven Levy. Meanwhile, there are tributes from xkcd and The Laugh-Out-Loud Cats.
Is it too soon to criticize Steve? Valley Wag don't think so. This article is pretty balanced and worth a read:
http://gawker.com/5847344/what-everyone-is-too-polite-to-say-about-steve-jobs