I'm a non techy in a big way but a little more savvy than a lot of my friends (20 years in the industry in one role or another and you pick up a few things), so that probably makes me around average as a home user. And everything I've read about Vista tells me that when I upgrade my home PC I definitely do NOT want it.
Those people who say it's great usually end up qualifying that with "of of course this was after I disabled this function, and turned that one off" - well I've got news for you guys, the "average" home user doesn't want that hassle & most couldn't do it anyway, they want something that runs well out of the box without technical fiddling. The vast majority of the new bells and whistles just won't get used, e.g. they don't want the OS to do indexing for them, they just want to stick it all in the relevant folder in My Documents or possibly a sub-folder there. The more complex it is, the more confused they get. And the more complex it is, the slower it gets for doing all the stuff we bought a computer for in the first place.
What the "average" user really wants is a PC they can take out of the box and immediately do reasonably basic stuff like web browsing, emails, games etc on without any hassle. If they thought about it, they would problably like it to be reasonably secure too. Full stop.
Techies like shiney new toys, so the designers put lots of them into Vista. But in the same way that not everyone needs web access on their mobile phone but just uses it to make calls, not everyone wants added "features" that complicate life on their home PC.
What Microsoft should have done IMHO is release Vista normal and Vista "Shiney Toys" versions, with the normal having all the "presumably good" upgrades and the "Shiney Toys" version having all the bells & whistles that complicate matters. Or just make the standard install be without all the extras and let people add them in a custom install