Having spent five hours yesterday unscrambling a friend's "new" laptop that came with Vista, no: Win7 isn't Vista masquerading. They just look similar
The sillinesses in Vista are mostly gone from Win7.
Her Vista would start up, and then do a BSOD - always 2½ minutes after start. If I waited and didn't log in, it crashed waiting at the login screen. If I logged in quickly, it crashed after her desktop was up. Nothing in the Event Viewer showed what was crashing. Turning off everything in MSCONFIG didn't make any difference. It would start and work OK in Safe Mode, with the limitations that brings.
In the end, we decided to install Win7 over the Vista, on the basis that should fix it. The Win7 DVD started, took a good look at it, and reported that two files on it needed to be "removed or replaced" before Win7 could install. We removed those two files, and Vista is working again. So she doesn't have Win7, which is probably a good thing since she isn't really a "computers" person.
My guess is that something in automatic updates glitched. Those are now OFF.