Hope Apple gets more people in quality control on the OSX side. A lot of bugs are still left over from Lion, and some new ones exists. Anyone with these same bugs? I don't know if it is my system, but these bugs have been bugging me for a LONG time.
System Preferences -> Software Update no longer shows what updates you have installed. So you can't check what versions of software you have installed and what updates were applied (especially any patches). No convenient way to check.
Unable to set Photo Stream options for upload only or download only. The OSX should have option to "Download only" and iOS devices should have option to "upload only" for Photo Stream. For example, if you have 1000 photos from iPhone, they are all streamed to your MAC. The next 1000 photos can also stream, accumulating on the MAC. You don't want the MAC pics to stream to all your iOS devices, because 500GB can't fit into 32GB!
Wi-Fi sharing of Ethernet doesn't work for WPA2
Mountain Lion lacks preferences for harddrive (check/change partitions, check size, defragment, etc)
unable to change password for me.com accounts when it is not your Apple ID. Odd setup. Lets say you have a gmail account as your Apple ID. then you get a me.com free email from buying an iOS device. If you change your AppleID associated with your gmail on apple, it also changes your me.com email password! That is so odd. If you use me.com account as Apple ID, and then add a gmail for email, changing the Apple ID through apple, does not change your gmail email password (obviously). I can accept Apple ID and email using same me.com account, changing one changes the other, but currently it is so confusing.
In Finder if you sort using date modified (typical for editing recent files), it shows correctly in list view (most recent modification near the top). But if you are actually in an app (like text editor), and select Open... the dialog (using date modified sort), the listings are in reverse order! Least recent to most recent within a category (the earlier section shows oldest modifications first, so you may scroll though thousands of files to reach the most recent near the bottom). Believe it or not, people who do a lot of editing of text files (like a website full of html files, this is a big bummer).
keyboard shortcut for international languages doesn't work. For example, lets say you turn on an international language like Chinese Simplified (PinYin). The shortcut for it is Control + Shift + P. It doesn't work. Also there is no shortcut to quickly get back to English. Fast typers need this working, not pausing to use the cursor. Low productivity.
iMovie is totally broken in Mountain Lion. Try exporting a movie that you've added an intro that is themed. After the intro. the movie gets stuck at the first frame for the rest of the movie.
And of course the biggest bug. Turning on Accessibility for double tap and drag, you can't immediately release and tap to move the cursor. The window is still stuck to your cursor!
Restarting OSX, also breaks your Ethernet sharing over Wi-Fi. This bug has been there SINCE SNOW LEOPARD!!!! Every time you reboot (like installing a software, you have to manually go into the settings, turn off wi-fi sharing, turn it on again. if not work, go into wi-fi setup, do nothing, exit setup, turn off wi-fi sharing, and turn it on again. over and over again, so that you can get your iphone to connect using wifi)
Anyone want to hear more? Hope this is not boring you, or making you feel uneasy because of the number of bugs.