I have Win 10 now as my main OS ... and its fine , things from the 16 bit era of win3.11/win95/win98 will not work (if Win10 will see a DOS app it just lulz at you). But if they have a 32bit stub in those old games , win10 uses its own HyperV OS emulator to run this game - its their renamed version of Virtual PC (even games that did not worked in Vista/win7/win8 , now work natively out of the box.. they update the emu daily) ... you can also use it to install older OS ... but i would recommend VMWARE 12 with win98 ... but hell win10 from day to day fixes itself so much its scary
As a OS in its self , all information is so clear and given to you ... its crazy
Games run crazy fast , even faster then in Win7 (from 5 to even 20 FPS more) ... speaking about dx10 games and up ... but even older work too fast , not kidding
Yes its collects data what you do , but only if you let it ... why it does it , well it has a AI build in named Cortana ... a real clever beast if it gets to know you ,and what you do (even when you block its net access) "Your 16bit game XXYYZZ that you tried to start four times , now will work . Should I start it now"
The thing is Win10 became a system similar to ANDROID , (or that APPLE thingi) when all things are a App similar to Android . A universal OS that wants to be on everything and help you run anything , but not be a jack of all trades then all previous OS where = We build the shell ,YOU build the app
So what does not work :
well QuickTime does not ... but for that you have this
http://tommynation.com/install-quicktime-windows-10/ (adobe product still are stuck on QT and well old WIN95/98 adventures need it that are build in Macromedia Director)
no ASPI , that means no DMA ... so no Advanced SCSI Programming Interface ... if you have a DVD on SATA or Ribbon Cabbles ... your forced to get a USB case for that ... there are solutions but now still in Beta faze like Frogaspi or others
all 16bit stuff will not work ... period , even win 10 will lulz at you with a pop up about it ... so VMachines are the only way to run old software (DOSBOX , VMWARE , or its inbuild HYPER-V) ... but what will work changes so fast its WOW
You have to manual disable windows update system (in services) to not use you as a P2P update server and hog your HDD drive
About start menu , well its a mix of old with new ... and it works fine ... but some people will miss the old winxp start , but for that you install CLASSIC SHELL
http://www.classicshell.net/
From Vista, windows Explorer became a load of crap ... does not show how much free space you have ,or closes itself (then moves to the next folder like in winxp) when you eject something (USb/CD/DVD/BD/HDD) but for that CLASSIC SHELL fixes some its issues , but for some you just install Explorer++
DRM from old games will not work ... new memory manager broke that DUH ... cracks are now the only way to run legal games that have SafeDisc/SecuROM/TAGES and STARFORCE ...
STARFORCE DRM drivers can break the WIN10 boot system ... but win10 is so HEAVY HEAVY EXTRA HEAVY ... did i mention BUGGERING PERSISTENT to make system restore points for every thing you install to C: drive ... your covered if something goes wrong ... making it a foolproof system
NO MIDI support = no sound fonts but you can fix that by installing CoolSoft VirtualMIDISynth
So as you can see Win10 is just a Shell now , not all in one solution like it was till WIN7 ... you have to install apps to it to make it work (it does not even have WMP no more , but an APP from WIN10 phone/tablets to run movies)...but for that you get MPC-HC with combination of VLC ... see Win10 now as LINUX ... but LINUX made for DERPY people
So what perks does it have right now :
App phone game from WINDOWS phones work natively ... yeah crazy ain't (it even has a app store with free phone games)
You can turn your PC into a Tablet ...
Inbuilt games recorder (only if you have a XBOX360/XBONE PAD) ... press the GUIDE button THREE times to activate a menu
Quick menu when you press WIN and X
Has a in build recovery OS , hidden on a hidden partition ... making recovering stuff easy
Games build in DX10 and up run ... from 1,5x to 2x faster ... the magic of Dx12
Some games run by native , that could not run in previous iterations (even some 16bit games ...) ... they update it constantly with new backward compatibility stuff , its crazy ... one day this game did not worked , the other it works natively (it uses the same principle as Xbone emulation of Xbox360 for some programs, special made VM profiles made for this app)