The overall poorer performance of every single application. The amount of hardware to maintain only a 10% performance LOSS over XP Pro is staggering.
the Aero interface hogs up over 430 mb's of ram when its idling.
They also killed ASIO in Vista, which is what most high end audio/video packages used for sound due to the low latency.

The only way to get ASIO support is to do the XP to Vista upgrade and already have the ASIO drivers installed for XP.

None of the Audiophile sound cards will run under the native versions of Vista as Audiophile depended on either ASIO or DX Sound. Creative Labs, (one of my early clients) is having a terrible time. EAX is dead in Vista. And Creative cannot get their drivers to run well at all under Vista. This is per Creative Labs.

None of the DirectX Sound filter plug-ins for the high end audio packages will work under Vista.

Mickysoft has not specifically stated whether an AGP or PCI Express (PCIe) video card is a requirement for Windows Aero, but they recommend PCIe video due to their greater bandwidth. There are some (damned few) PCI cards available that are compatible with Windows Vista as well.

These are not bugs. These are design features of the OS. MS's TechNet forums are covered with things like this.

You'll have DRM issues ... wait until you try to copy any HD content which has been flagged as copy protected.

There is no amount of RAM which will get back the lost performance ... None. The sheer number of background processes and overhead dictated by DRM being imbedded in every single driver and API in the OS has raised the overhead significantly. There is no way this OS will ever be as fast as XP, on the same hardware ... That is not an opinion, It is a technical reality.

I have several thousand dollars worth of software rendered useless by Vista, this is not about tech crap. It is about functionality. If you like less performance than XP, on faster hardware, then go for it. If you want your high end audio/video software to no longer run, then go for it. That is not about tech either. It is about bang-for-the-buck.

There are so many issues with various hardware and software packages, it would be irresponsible for anyone to say Vista is a-ok for THE MASSES.

Saying that Vista is all peachy-keen is just wrong. The last thing anyone needs is to be misinformed about this.
Most "casual users" will need to replace ALL mickysoft software and utilities ... and keep a XP machine around to run their legacy games and stuff.