My computer currently barely runs on Vista (as far as I can tell simply because things are getting more processor/memory heavy and my computer can't handle it weighed down after five years of use), so I'm not making any changes to it.
I'm just waiting for the release, when I will be upgrading by the time honoured "buying a new computer" with a reasonable amount of memory.
From what I've heard from my brother, who is building aspects of it (so there's a certain amount of biases there), Windows 10 is a lot of things that previous Windowses just weren't and I'm excited to make the leap and watch it progress. I've never used WMC (I had to look up why its loss is a big deal to some people), but then I've always consumed media through third or fourth parties and I've never owned fancy devices that are connected together like Apple makes everything one giant conglomerate.
Vista was and is a very bloated OS and resource intensive. I've had really good luck running 7 on a Vista and even XP machines without any stress on the hardware. Matter of fact, my Toshiba (the $5.00 computer) is a Vista machine and its a bargain basement model. 1 GHz Processor. I did upgrade it to 4 gigs of ram because 1 gig just doesn't cut it for me.
As for WMC, I use Virtual DJ for most of my media needs. Granted the EQ is more limited than Media Player but I can live with that.
I'm thinking of making my primary computer a dual boot for 7 and 10.
Rumor has it this is the last OS Microsoft will make. Instead they will do upgrades to the new OS sort of like what happens with Chromebooks.
As stated in an earlier post, you can upgrade/get 10 for free for 1 year after release. Upgrades will be rolled out incrementally according to machine specs from what I understand. Also you can run it on all your machines so no separate licensing required. Another unprecedented move on the part of Microsoft.
Cortana is a nice addition. You can tell her to search for stuff (I had her look for the number of Trader Joe's in Greenville and she popped right up with it) and to open apps. It's kinda fun to mess with her