The iPhone revolutionized the smartphone market and was an immediate hit with consumers. Its long list of innovations, starting with its huge (for 2007) 3.5-inch multitouch color display, exposed the hard-to-use clunkiness of just about every smartphone that came before it. And the iPhone's App Store, which opened in 2008, brought an app-oriented culture to mobile devices that thrives to this day.
Perhaps the best example of the iPhone's influence is the imitators it has spawned, most noticeably Google's Android platform, which has surpassed the iPhone in global market share (and arguably influence as well). Recent iPhone upgrades may seem less than inspired, but that's probably because Apple got the smartphone right the first time.