After I updated to Mavericks, the font smoothing is terrible, tried playing with the setting in system preferences (didn't restart yet) and nothing changed.
I have a 15 inch early 2011 Macbook Pro with high resolution anti-glare screen (not retina)
Here's Finder menu bar in Mountain Lion
In this example you see that the left of "F" in "File" is noticeably fuzzier in Mavericks.
The problem is all over: window bars, menu bars, web pages (Chrome & Safari), apps, etc.