I did get some warnings about not having some sysprep files in place. That was a little scary, but I had a fallback path (the old VHD). If the new VMWare VM was broken, I would only have lost some time and gained some experience. I ignored the error. (From googling around, those files can be obtained from Microsoft and that might be worth doing, if you are converting a large number of machines.)
The tool converted the VHD VM to a ESXi VM and placed on my ESXi host. Using the VSphere management console, I started the new VM and had a look. I expected that I would have some slogging to go through, maybe I'd have to download drivers for the VMWare-specific "hardware".
While the VM was booting, I was distracted by another task. When I got back to working on the VM a few minutes later, I found that it was installing 59 Windows updates and was humming along. When it finished installing the updates, it rebooted. I could then log in using my old credentials. Windows complained about having been moved to "new hardware", but it allowed me to re-enable the license with just a few mouse clicks. No phone calls, no drama. I then updated the virus software to Microsoft System Essentials from the older Microsoft product.
I expanded the desktop to 1600x1200, to match my venerable Dell FP2001 panel. (This Dell is the best monitor I have ever owned. Between 1990 and 2001, I owned CRTs from Princeton, MAG and Sony. They all died. I even had the MAG fixed once and it died again. I have been using my Dell for 12 years. I've never had a problem with it.)
I configured the VM to use one vcpu. It is pretty snappy, maybe a touch more sluggish than running on my three year old Lenovo T500. wprime says that the VM is only a little slower than running natively on the Core2 Duo in my laptop.
So, the whole process went smoothly and I could see using the tool to do mass-P2V-ing of systems.