I can sympathise with much if not all of what this guy is saying. My Aunt recently bought a new Mac, not really knowing how to use OS X. I'm pretty familiar with most versions of OS X, but found myself struggling to justify to her the usefulness of quite a lot of the UI mechanics of the OS. What annoyed me the most was that the parts of the OS she found most confusing seemed almost universally to have been introduced since 10.6.
The 10.7+ habit of remembering open windows seemed to flummox my Aunt and continues to irritate me on a daily basis. "But I closed that window, why has it come back?"
Take Mission Control. Exposé was incredibly simple conceptually and worked very well for most people. I don't hate Mission Control, but explaining its workings to my Aunt was somewhat difficult, and I'm still not convinced that it's better than Exposé.
I feel like a lot of the simplicity that originally attracted me to OS X has been convoluted recently. And don't get me started on stability, performance and skeuomorphism...