I've installed in a couple and had friends do the same. Only one problem so far - the USB drivers didn't update and the USB mouse failed. Took a little effort to get into the control panel / system / device manager to delete the USB drivers. After that the new drivers were installed and everything works quite well.
The pop-up blocker is quite nice. I already have Zone Alarm so I haven't tried the firewall. Overall impressions are good for me.
However, I'm still advising against it, since I don't want to be technical support if a problem does arise. I'll give it a couple months until I suggest the non-technically savvy people install it.