Leave it to Apple to turn the time consuming process of upgrading an operating system into a simple update through the App Store. This morning, I upgraded my second generation MacBook Air (with Intel Core 2 Duo processor, 4GB of RAM and flash storage) from Snow Leopard to Lion and it couldn't have been easier. Let me take you through the process.
Before upgrading to Lion, make sure Snow Leopard is updated to the latest version and back up your entire computer to an external drive through the Mac's Time Machine, just in case something goes wrong during the OS switch. Backing up through Time Machine is as simple as connecting an external drive, setting the drive as your Time Machine disk and clicking the "Back Up Now" option, but it will take a while, potentially longer than the actual Lion upgrade. I got this done the night before Lion hit the Mac App Store.
Ready to upgrade? Just open the App Store
Just like buying an app or song through iTunes, downloading Lion is simple and inexpensive. You won't find a cheaper OS upgrade unless you're a Linux user. Assuming you store your credit card information with Apple, the most cumbersome steps are opening the Mac App Store and typing in your password. Plugged into a power supply and on my home Wi-Fi connection, I downloaded the 3.5GB Lion in 40 minutes, during which time the computer functioned normally, allowing me to continue working. It is recommended that you have at least 10GB of free disk space to complete the upgrade, but once I was running Lion I noticed that my 56GB of free disk space was roughly unchanged.
Time for a little disruption
After the download comes the most disruptive part of the upgrade, the installation itself. After a few minutes of preparation, your system will restart and become unusable for a time. The dialog box told me it would take 33 minutes but it turned out to be 15 minutes or less. Expecting it to take longer, I left the room and it was finished by the time I came back.
After the upgrade, back to normal
After the installation and restart, and me typing in my system password, I was back in the Mac operating system and everything I've ever installed was still there, plus a few additions. A short setup assistant demonstrates two-finger scrolling, which lets you navigate content by moving your fingers up and down and left and right. Facetime also appeared in my dock, as did the new Launchpad and Mission Control.
Your new Launchpad
Clicking Launchpad gives you an iPhone or iPad-style display of your applications as icons, which can be rearranged and scrolled through by moving two fingers left to right on the trackpad.
Perhaps even better is Mission Control, which gives you a quick view of all open applications, as well as your four "desktops" and dashboard. You can get to Mission Control by clicking the dock icon or putting three fingers on the trackpad and scrolling up. Moreover, you can move from one desktop to another at any time by using three fingers to scroll left or right. This adds convenience if you keep many applications open at once and like to organise them in groups.
One thing I do not like about Lion is a switch in default up-and-down scrolling behaviour, which was reversed to replicate iPad functionality, in which you're supposed to feel as if the page is tethered to your fingers. But it feels less natural when you're not actually touching the screen. If you're like me and don't like the change, all you have to do is navigate to system preferences, click on trackpad and uncheck the first box under "scroll & zoom" to revert back to the way it was under Snow Leopard.
Windows survives the upgrade
One slight concern I had was whether the several Linux and Windows virtual machines I run would be affected. As you can see here, I'm running Windows 7 in a Parallels virtual machine, and it survived the Lion upgrade fully intact. Still, before upgrading it's wise to investigate whether your applications, particularly ones built for the older PowerPC architecture, will run on Lion. As a long time Windows user who bought his first Mac less than a year ago, this wasn't an issue for me.
Upgrade to Server
Now that we've gone through the upgrade process and examined the most immediate changes, go back to the Mac App Store and check out "OSX Lion Server." Apple is letting anyone turn a desktop computer into a server. If you own a lot of Apple devices or run a small business where people use Macs, the extra file sharing capabilities, website, calendar and mail hosting might make the extra price worth it. For myself, I'm saving my money for now because I get all the file sharing, mail and calendar functionality I need through various free web services.