My only issue is DX12 - are games of the near future not going to use DX12? There is already one new AAA title on the way in March that is DX12 - no Win10, no DX12, right? PC gamer has reported that Microsoft has stated unequivocally that Windows 7 will NOT be getting DX12 updates. So, as much as I'd prefer to stay with Win7, I'd also like to use the new products and games that will be created and require DX12, especially a lot of the coming VR stuff - but not JUST those games, a lot of mainstream stuff will likely start being Dx12 as well, such as RTS titles like Ashes of Singularity.
I ended up trying Win10 much the same way Latrobe did - When installing AH beta my TrackIR program flipped out, and then locked up, and no amount of reinstalling/registry edits and retries could make it stop locking up my PC when launched - Natural Point's techs spent 4 hours in my PC remotely trying to figure it out, and couldn't, so as AH and a couple other games were the only thing that specific PC is used for, reinstalling Win7/format/ wasn't a tough option. Since I had to do this anyway, I figured why not try the Win10 upgrade as I was going to wipe the drives anyhow. Win10 did solve the TiR software problem - again I realize it's just a temp/masked fix, that whatever caused the TiR software to slowly start locking up the PC is out there probably still, I just wanted to see Win10. WAY too much stuff to have to turn off to get it "sort of" secure, and you CAN'T get rid of Cortana regardless of what you try, aftermarket "fixes" and otherwise.
The one thing I think is unforgivable is how Microsoft has the updates set to use your PC as a torrent like server helping MS distribute their product with YOUR bandwidth. The majority of unsavvy PC users will never figure this out and switch it off, and MS will happily steal their bandwidth, and with the majority of ISP plans having data caps now, and with the majority of net use being Netflix and other bandwidth hog programs - this is a very, very dangerous thing MS is doing, and is going to open them up to suits IMO. When folks start getting overage bills from their ISPs for MS using and breaking THEIR data caps, TOS or not, I can foresee lawsuits over that, particularly with "forced" upgrades where there is no actual "click" of an "I understand and agree" box. And even with that box, you can't sign your rights away, including being stolen from.
DX12 support or lack thereof is my only concern with Win7 - of all the OS put out by MS, it's by far been my favorite, by an order of magnitude. In fact, it's pretty impressive considering what a giant POS the predecessor Vista was.