I like the way things are spaced out and the flatness, but I don't like the translucent windows. That's Windows 7 and it looks crap. I do think OS X needs some important changes, but I don't think it looks aged (skeuomorphism ages very quickly as we know).
I think the main thing that OS X needs is a vastly improved Finder, where icon views, window sizes and sorting is SIMPLE and CONSISTENT. Right now if you open a Finder window and set the icon spacing and the window size, that will only apply to THAT particular folder and nothing else. You'll be stuck with the default view forever unless you change each and every folder manually which could potentially take tens of thousands, if not millions of years, if you have many folders on your system. Now I don't have that much time unfortunately.
Also SMB needs to be fixed or basically just trashed entirely and rewritten from zero, as it does not work and has never worked properly.
And TextEdit needs to calm the hell down and stop presenting me with an Open File dialog whenever I open it. If I wanted to open a file, I'd have gone to Finder and double clicked the file. Navigating to file locations from within the Open dialog is what you did in the 90's.