As the iPhone turns five years old today, here's a look back at WSJ columnist Walt Mossberg's reviews of each iPhone over the years. Click on the links for the full reviews:

Our verdict is that, despite some flaws and feature omissions, the iPhone is, on balance, a beautiful and breakthrough handheld computer. Its software, especially, sets a new bar for the smart-phone industry, and its clever finger-touch interface, which dispenses with a stylus and most buttons, works well, though it sometimes adds steps to common functions.

If you've been waiting to buy an iPhone until it dropped in price, or ran on faster cell networks, you might want to take the plunge, if you can live with the higher service costs and the weaker battery life. The same goes for those with existing iPhones who love the device but crave faster cellular data speeds. But if you already own an iPhone, and can usually use Wi-Fi for data, you probably should hold off and get the free software upgrade before deciding whether it's worth getting the new hardware.

In my tests, both the new phone and the new operating system performed well, with a few small exceptions. I believe the two strengthen the iPhone platform, make it likely the iPhone will continue to attract scads of apps, and are good for consumers. But I also regard these changes as more evolutionary than revolutionary, and I don't think this latest iPhone is as compelling an upgrade for the average user as the 3G model was last year for owners of the original 2007 iPhone.

In both hardware and software, it is a major leap over its already-excellent predecessor, the iPhone 3GS. It has some downsides and limitations-most important, the overwhelmed network in the U.S., which, in my tests, the new phone handled sometimes better and, unfortunately, sometimes worse than its predecessor