But there are certain (non)usability things it introduced which I didn't think were great, actually. Window close button next to the minimize and other controls. Classic MacOS did it right by putting it on the far other side of the window where you couldn't accidentally click. The Start menu broke the whole OO metaphor by adding a deep tricky menu system. Right-clicking context menus all over the place. Task bar at the bottom dynamic depending on what is running means hard to use muscle memory and predict where a given tile will be.
Overall it was very good for the time. Though in fact I personally think the more 'flat' and minimalistic interface of Windows 3 aged better. This faux-3d bevels etc thing didn't age well. Was a novelty product of the time that NeXT kinda began and everyone followed for a bit.
The actual "operating system" (really a shell for MS-DOS) in Win95 was terrible.
I still don't think Apple made the right UI choices in their transition to OS X.
Something that looks more like the early Rhapsody copies would be nicer.
Back then we were fighting tooth and nail to undermine MS's monopoly, and Linux as you see it today is the product of that.
I will admit the first times I saw the Win95 interface I found it appealing. Though they actually cribbed a lot form the NeXTstep UI, and I'm much more fond of that.
I prefer the Sun OpenLook UI for nostalgia value, myself.