I honestly never understood people hating on Lion. Maybe initially because it was a little different and jarring. And I know Mountain Lion runs a good bit faster, but c'mon it's not THAT bad.
For many it was a departure from Mac OS X and letting Mac OS X (now only OS X, the Mac has been taken away be more like iOS, which in itself is understandable from Apple's POV (iOS devices sell rather good, why not get some of the "good" stuff from iOS to Mac OS X and see, if it helps selling even more), but leaves many people, that came to a Mac long before the iPhone was released or even thought of, and probably many others, in the unknown.
Where will OS X go next, or what will be taken away next, is a constant question for those, me included. They already took away proper Spaces for me, and since then, I have tried
Mac OS X 10.7 Lion twice and
OS X 10.8 Mountain Lion twice, but always reverted back to
Mac OS X 10.6 Snow Leopard, even with TotalSpaces, which is still not as good as Spaces.
There are many other things like Facebook and Twitter integration, I do not care about those, but currently those are in fashion and enjoyed by many people, and do not seem to go away that quickly (hopefully only another decade) and so on.
Imagine going from Spaces in
Mac OS X 10.6 Snow Leopard, looking like this
to Mission Control in
Mac OS X 10.7 Lion, looking like this
Of course, not everyone uses that many Spaces, but Mission Control seriously hampers the usefulness of more than four virtual desktops.