With OnLive Desktop, you get a pure Windows 7 and Office 2010 environment that can't interact with the device you're using it on or the content available to that device; that is scaled inappropriately for the iPad's screen resolution; and that is available only when you have a broadband Internet connection. The service isn't consistently accessible; the error message blames the Internet connection speed, but I don't believe it. Each time this happened, I could get access a few seconds later on the same Wi-Fi network and back-end broadband connection. That feels like a capacity issue at OnLive's servers or cloud provider. (OnLive's Web page does note that access to the free service is "as available.") Worse, that error page has no retry button -- or any control -- so you're stuck. You have to leave the OnLive Desktop app or close it using iOS's multitasking dock, then reopen it, to try again.
Running a non-touch-savvy operating system like Windows 7 is awkward on an iPad or other tablet operating system, but at least VDI products such as Citrix Receiver provide some mapping of the iPad's user input to Windows to bridge some of the gap. OnLive Desktop does none of that integration. Of course, products such as Citrix Receiver require you have your own VDI back end, a complex and expensive investment, which is why OnLive Desktop is appealing conceptually.
OnLive Desktop is available for free, which is no bargain given its overall uselessness. OnLive plans to offer paid subscriptions starting at $10 per user per month that increase the included storage capacity from the free version's 2GB and provides "prioirity access" to the OnLive servers. That lets you install your own Windows apps, as well as one that is IT-manageable (meaning IT can specify user entitlements to Windows apps). These service versions are not yet available, so I could not test if they addressed any of the free version's shortcomings.
Still, I can't imagine anyone using OnLive Desktop for real work. I suppose if you have Office projects that use capabilities not available in native iPad apps -- such as the need to edit style sheets or do revisions tracking in Word documents -- OnLive Desktop could be useful when you have no other option and can't wait until you get to a real PC.
Unfortunately, despite the concept's clear appeal, OnLive Desktop's Windows-via-the-cloud offering is too awful in its current state, and it's a great example of why you can't stick one operating system onto another without any integration.