I personally haven't seen transparency effects having any significant effect on gaming performance. At least in exclusive full screen mode, DWM backs away. In windowed mode however, desktop compositing will introduce mouse input lag due DWM's vertical sync, which is otherwise nice to get rid of screen tearing when scrolling web pages, documents, ... I just remembered one of the compositors for X11 (Linux and the like), Compiz, has an option for limiting its refresh rate, if you set it to "monitor's refresh rate - 1", you get smoother mouse movement with VSYNC while on the desktop. Maybe Aero effects themselves were more of an issue on older hardware.
I'm nuts about Aero, so Big Muscle's Aero Glass is always installed. I remember @NoelCposted some benchmarks one time with Aero Glass enabled/disabled and they didn't show any significant performance degradation (was there any at all?). Modern GPUs are pretty powerful, even cheap ones are good for the basic desktop composition.
Wine can be a total hit or miss. But imagine if all that effort went into developing quality ports of native applications. I think it would do well to improve bad parts on the Linux desktops and the like. Microsoft would be forced re-think their strategies.
Their whole pushing of Windows 10 surely left some effect. It seems it's almost everywhere now. Pick a random shop or dentist office or whatever. The same place probably clinged to Windows XP back in 2010, today, they're on Windows 10, as if it was the best thing ever.
It sucks, because I realized after running Windows 10 for about a year and half that Windows 8.1 isn't perfect neither, although it's very close. If one could just bring some of the good things back to 8.1...
It seems however that Windows 10 may be necessary evil for some scenarios. Supposedly its new display driver model has performance benefits even for cross-platform Vulkan API.