It sounds like the author simply doesn't like change and is looking for things to pick apart. Yosemite is faster on every machine I've installed it on and I think the new interface is a new, modern, fresh take on OS X. If it's slow or dropping frames, perhaps it would be best to investigate and diagnose if your machine is OK or not before complaining. Of course, interface preference is subjective but I suspect most people simply don't care that much.

Change is hard, but if you go into it with this attitude you won't ever want to upgrade or try anything new.