I find new OS Xs for iphone, ipad, all Macs, hugely inferior to prior versions. Speed, appearne, effectiveness, everything!
Nothing is ever liked/loved 100% by all users.
Simply put, you're wrong.
Putting aside churlish remarks about the looks of the UI elements, there are numerous, and listed, improvements and new efficiencies in each of the latest iterations of OS X and iOS. You can read about them on Apple's web pages, assuming you can pull your head out, and try them out yourself. As is usually the case with Apple updates, you often find yourself wondering how you lived without (feature X), though of course as is also always the case, there are features you don't think you'll use and you are right, and a few feature you didn't think you were going to use and you turn out to be wrong.
For me, the ability to send and receive SMS, iMessage and phone calls on my Mac as well as my mobile devices has been a life-changer. Being able to send an SMS message by clicking on a phone number in an email message in Mac Mail -- fantastic! The notification center generally and specifically how I can add certain widgets to it -- enormous time-saver. Spotlight and Family Sharing -- WAY better and less confusing than the previous implementations.
Mail has some new features I like a lot, but is clearly still in the polishing mode and has some issues. Instant Hotspot (a feature I **constantly** rave about and use all the time) actually works less reliably in 10.10.2 (beta) than it did in 10.10.1, which is disappointing. And don't even get me started on how much better the cleaned-up Contacts and Calendar are over the previous versions.
But these are just the features I like in Yosemite. There are many more I haven't even bothered with, like audio messages in Messages. As for iOS 8, I think the look could use a bit more refinement but in terms of functionality its been fantastic for my iPhone 5s.
The Health app is making me aware of my step count (and how alarmingly low it is), the Time Lapse option on the camera is fantastic, the ability of apps to have extensions into (for example) Photos (which kicks iPhoto for iOS's buttocks) means I have a much more streamlined photo-editing workflow there that is ridiculously faster than before, notifications are way better, the gesture-based mail control makes short work of my inbox, and predictive text is a huge boost given my large vocabulary.
Again, there are things in iOS 8 I don't at present have any use for, such as quick video iMessages -- that's more for the kids, methinks. The expanded use of TouchID by other apps, however, is in my opinion the Best Thing Ever that's happened thus far to the iPhone -- and I haven't even been able to try out Apple Pay yet.
Saying iOS 8 or Yosemite are not as good as previous versions is simply ignorant and close-minded. A better approach, IMHO, is to embrace the new features and improvements (LOTS of improvements in stuff from Mavericks and earlier that I haven't even really gotten into) and send bug reports about the things that don't work. Whining has never fixed a single bug yet.
As for the design, before you send off a letter to Tim Cook about how "ugly" it is, you might want to check your mantlepiece for the number of design awards you've won, and then ponder whether your critique will be taken seriously. That's not to say you can't not like it -- I think it over-uses white space and has a few other minor flaws, as do most people -- but you might find it grows on you if you give it an open-minded chance (it did with me), and of course Apple has no intention of "freezing" the design now or ever. Take a look back at OS X 10.0 and then take a look at OS X 10.8 if you don't believe me.
I promise you this -- five years from now, this forum will be full of people who hate the look of OS X 10.15 and iOS 13 and long for the good old days when colours were muted and flat.