Once I had installed the CD/DVD-sharing software on my MacBook Pro, I found another option under "Sharing" in System Preferences that allowed the Air to share the DVD drive. I popped in a DVD, gave permission to share the disk, and voila - the disc icon showed up on Air desktop, just as if it had a built-in drive.
Next, I tried the Migration Assistant, the Apple utility built into Mac OS X to migrate files between a user's computers. I typed in my password, told it I wanted to transfer files from another Mac, launched Migration Assistant on the second computer, told it I wanted to migrate files to another Mac, typed in a password, and I was ready to transfer files. It was as easy as pairing a wireless keyboard or mouse. Pretty nifty.
File sharing wirelessly from another computer's hard drive also worked well. I copied a 155MB file from my MacBook Pro to the Air in an hour and 28 minutes. The fact that both laptops use the faster 802.11n Wi-Fi standard no doubt helps, and Apple recommends that if you're transferring files, you should keep the computers close together to ensure maximum transfer rates.
While those options should go a long way toward assuaging worries about the Air's lack of an optical drive, personally, I'd still opt for the US$99 external optical drive, just in case you need to access a CD or DVD while on the road. That way, you don't have to have another computer for optical disk access, and you don't have to jump back and forth between two computers simply to install files from a CD or DVD. The external drive weighs only 312 grams, so it's not going to add substantial weight to your laptop bag.
I'd also consider getting the US$29 Ethernet-to-USB adapter. Wireless networks may be growing in popularity, but they're not everywhere yet. The USB adapter Apple sent with its review hardware worked as billed, allowing me to connect to my network at work with no problem.
I do have a little concern about the long-term durability of the little door that swings down from the right side of the Air to expose the laptop's ports. Little doors break. This one doesn't feel particularly flimsy, but the USB port felt tight whenever I connected or disconnected the Ethernet adapter, leaving me worried that I was just one tug away from breaking the port door.
For the users the Air is aimed at - execs who lug around laptops all day long, road warriors or students who cart their computer from classroom to classroom - Apple's latest creation seems to be a solid choice. It does enough of what it needs to do to be a viable option, and for those who need more ports for peripherals, Apple has provided workarounds that work. But it's the form, more than the function, that will sell this laptop.
The more time I spent with the Air, the more I came to see it as analogous to having a second car in your driveway. A MacBook or MacBook Pro represents the family hauler, basically doing everything you need for it to do with all the space and horsepower you could want. The Air is more like the weekend two-seater convertible that you enjoy driving even more, but only for specific reasons. You may not always be able to use it like you would the other vehicle, but when you're headed out of town on a road trip, it's the one you almost always want to take with you.