It's hard to imagine what more a Windows-on-Mac virtualization application might do given the software's undeniable maturity. If Mac-on-Mac virtualization -- the big new capability in Desktop 7 -- is the most important next step, then Parallels should have taken a little more time to make it easier.
Windows 7 users might see a speed boost. Although Parallels Desktop 7, which has an Australia recommended retail price of $89.95 for the full version, promises to run graphics 45 percent faster than Version 6, I saw a mere 8 percent improvement in 2D rendering, based on the PassMark benchmarks. I did get a 44 percent boost for 3D graphics, so gamers and simulators should see a notable improvement. But note that Parallels Desktop does not support DirectX 10, so some video-oriented games and applications won't run.
Overall, PassMark showed Windows 7 running 9 percent faster in Parallels 7 versus Parallels 6. That's not bad, but keep in mind such synthetic benchmarks tend to overstate what you'd get in real-world performance. For most users, I don't think it justifies an upgrade.
Parallels 7 vs. Parallels 6
Parallels Desktop 7's other enhancements include support for Mac OS X Lion's full-screen mode and Mission Control interface, support for the AES-NI encryption standard for Windows VMs, and easier sharing of printers and the Mac's built-in camera. Version 6 can run on Lion as well, but it does not support Lion's new gestures or Mission Control.
The $23.99 Parallels iOS app from the Apple App Store lets you access both Mac OS X and Windows VMs, as well as the underlying Mac OS X, from an iPad or iPhone. The previous Parallels app for iOS did that just for Windows VMs. Of course, virtual desktop clients for running Mac OS X on iOS are easy to find, and there are good free ones, so the main value of Parallels' enhanced iOS app is the unified virtual desktop. Plus, the iOS app works with both Parallels Desktop 6 and 7, so you don't need an upgrade to Parallels Desktop 7 to take advantage of it.
These Parallels Desktop 7 enhancements are welcome, but I'm not sure they're worth the cost of a $49.95 upgrade ($89.95 for the full version) to most users -- especially just nine months after Desktop 6 was released. What might entice you to upgrade to Version 7 is Parallels Desktop's new ability to create Mac OS X Lion VMs, with which you can run virtual Mac instances on your Mac, such as for beta testing or configuration testing.
Previous editions of Parallels let you set up Mac OS X Server VMs, but not VMs of the desktop OS. Apple removed its restriction against desktop OS VMs in Lion (you're permitted to run two Lion VMs on your Mac), and Parallels quickly enabled that capability in Desktop 7. (Note: You still can't create VMs of previous Mac OS X desktop versions, as Apple hasn't changed the licensing terms for Snow Leopard or earlier versions to allow it.)
Virtualizing Mac OS X Lion
Unfortunately, Parallels Desktop 7 gives you only one easy way to install Mac OS X Lion on a VM, but it's painful: You download the 4GB installer file from the Mac App Store, which means waiting for one or more hours.
The way Parallels handles Mac OS X installation via the Mac App Store means you can create only clean installs of Lion; there's no simple way to transfer an existing Lion environment to the VM as there is for Windows VMs.