I use PowerDVD 10 for that - because I watch Bluray and no DVD's.
I appreciate the lack of support on the Windows 7 Media Player because I can use something like Shark 007 CodecPack to allow me to play back every file that I want and how I want (DXVA is the magic word here).
DVD playback expensive? Let's just say that VLC-Player is a pretty cheap alternative (freeware).
Windows 8 is as far as I can tell the exact same as Windows 7 and there are some improvements to that (Recovery and Refresh-functionality). Let the MetroUI stand aside - it's for the "multi-device-os"-badge. Not for Desktop-Usage.
I don't think that it will "suck" and be "sh*t" ... I'm gonna take a look on it when it's fully released and then I'm going to judge. But what I read and saw of Windows 8 so far seems kinda promising and nice. Nothing horribly awful so far.