10.8.5 working great so far on my laptop. I believe my boot times are even faster than 10.8.3. I reluctantly updated after I saw 10.8.3 was no longer given access to appstore. Unfortunately for me, I had not installed Xcode before 10.8.5 was released QQ.
Small issues;
Install hangs with "bluetooth setup assistant" -- Easy just disable bt from bios, and toggle wifi switch off during install.
Post install I did have to update to the 10.8.4 S/L/E folder because I was doing the combo update from 10.8.3. Also Wifi did not work as expected, so I had to replace the airportd file.
Also a warning to those with 10.8.3, if you decide to update, you will need to update the 10.8.4 kexts, specifically IOFamily & AHCIPort, from outside of OSX. The combo update has a built in reboot step you cannot fix or do anything about as far as I know. So do not upgrade if you do not feel comfortable in single user mode or have a windows partition with MacDrive (awesome software).
If you don't feel comfortable in Single User mode yet, start practicing, you're going to want 10.8.5 eventually