Well, I installed it, everything went fine, then on a reboot it would turn on, lock up before the XMB appeared, then shut down about 10 seconds later. A format of flash1 fixed this, and it booted up, but with no sound. Another freeze, and it shut itself down, but came back on fine with sound. PSPstates still works with the patch, but I did manage to lock it up (although I hit load game while the memory stick access light was still flashing from the save state,, so that may have been my fault). Everything else appears in order. Another problem people seem to be having is that their ISOs won't load, but this is probably due to the fact that for some reason installing this update resets the settings you might have for a no UMD driver. Using the recovery menu or VSHmenu (or whatever its called) can fix this easily (although it also seems to be the case that VSHmenu is disabled too so you might as well just hit recovery on first bootup and fix both of those)
So I dunno if these problems are common or if I just had bad luck, but if you're not the type who enjoys tinkering around with this stuff or if you're not sure what you're doing, you might hold off on this update.