- I've had worse upgrades, and I'm glad I was able to skip Lion -- the closest Apple has come to a Vista-class OS X debacle.
- Mission Control and Full Screen are made for my 11" Air, but they're a bit awkward on my iMac. I might change my old and unloved "Magic Mouse" to Apple's Magic Pad. A lifehacker article helped with changes to Spaces, but this tip in comments is key: "You can assign applications to a space without any addons. Just right click on the item in the dock, and do Options > Assign To > This Desktop". Not all apps have this ML-specific feature; Aperture does but iTunes doesn't. [Turns out this is a bug, iTunes should have the option. See below.]
- Ran Mountain Lion on a secondary machine for a few months. So I know I can adjust to the mouse direction inversion.
- Upgraded or abandoned a number of apps based on experiences with the Air prior to transition. FileMaker Pro and VMWare Fusion of course, but I looked at all the apps I use and either removed or upgraded them. Brought everything from App Store up to date that could run on Snow Leopard. Removed Rosetta apps (obsolete games for kids mostly). Removed Spanning Sync (no longer useful).
- Uninstalled all PreferencePanes.
- I should have removed all Login Items but forgot, created minor issues (below).
- Disk Utility Verify Disk.
- Uninstalled Citrix apps, my wife relies on that. I have a somewhat ML compatible version I'll install soon.
- Uninstalled Magic Prefs, an app I've used to make the Magic Mouse somewhat tolerable
- Attempted iCloud migration, that was a fiasco. I'm getting ready to retry with teeth firmly gritted.
Upgrade issues and bugs
- Ran into a known bug with Login Items (see below) - esp. “SpeechSynthesisServer.app".
- I had multiple failures with downloading Mountain Lion and a known bug with App Store "unknown error occurred" messages. (See below).
- I was unable to save the Mountain Lion installer. (below)
- When opened in it's Snow Leopard 'space-2' the iTunes Doc context menu was missing its 'Assign To' options. They were shown in other Spaces. I had to use those options in another Space to restore the menu in all Spaces. Looks like a bug with converting SL space-assignment prefs.
… The document SpeechSynthesisServer.app could not be opened because it is damaged or incomplete….
… I think this bug may hit people whose user accounts have gone through a few versions of OS X AND are going directly from Snow Leopard to Mountain Lion. In my case my user account started out with 10.2 - so it's picked up some cruft.
There are several items in my non-admin user Preferences:Users and Groups:User:Login Items that are not in my Admin account user including an item called SpeechSynthesisServer. It had a yellow warning triangle next to it and the data type was unrecognized.
I removed it from Login Items, logged out, logged in, and the bug was gone. The LoginIn item is referencing a system app, that app is still present post upgrade: /System/Library/Frameworks/ApplicationServices.framework/Versions/A /Frameworks/SpeechSynthesis.framework/Versions/A.
I suspect the app is still important. DON'T TOUCH ANYTHING IN SYSTEM/LIBRARY. Just leave it alone iTunesHelper was also on the one user's LoginItems and I removed it.
I think there are a couple of bugs with the Login Item migration from SL to ML. For example, a disk image I mounted showed with a yellow icon too. I removed it, added it back in, and it was fine.
The known App Store "unknown error" bug and a probably App Store download bug
I was unable to successfully download the Mountain Lion Install from the App Store; two attempts failed with an App Stoer error message "An Unknown Error Occurred". I'd saved a copy from upgrading my Air, so I had to use that. During this process I ran into a bug with App Store error messages. I think there are two bugs here:
- If the "an unknown error occurred" error appears after a failed App Store download, it will prevent future downloads. The fix is to use App store menu item for logging into your account and click the button to reset app store warnings.
- I wonder if under some conditions a failed download can get "stuck" and block future downloads. I haven't yet down this, but I wonder if cleaning App Store caches would help .
 from Apple Discussions, C Samit
… try deleting the cache, cookies, and preferences associated with the App Store. Quit the App Store if it's open. Now open the Finder. From the Finder menu bar click Go > Go to Folder Type or copy/paste: ~/LIbrary/Caches/com.apple.appstore Click Go then move the Cache.db file from the com.apple.appstore folder to the Trash. Type or copy/paste: ~/Library/Cookies Click Go then move the com.apple.appstore.plist file from the Cookies folder to the Trash. Type or copy/paste: ~/Library/Preferences Click Go then move the com.apple.appstore.plist file from the Preferences folder to the Trash.
After installing Mountain Lion I tried the App store download -- again using my User account. Again I canceled and it did not appear in my Applications folder. So either Apple has changed the download, or the trick for getting a local copy of ML only works for Admin accounts. This could be a permissions issue.
Also, I had to restart Google Earth so it would add its Login Item back.
Lastly, like all updates this one forces Spotlight to reindex. The combination of Time Machine/Capsule backup and Spotlight reindexing brings my system to a standstill. I recommend letting Spotlight finish before reenabling Time Machine.
Update 2: A major regression with Slideshows.
Mountain Lion includes many new slideshows, but only the "classic" supports dual monitors by showing different images on both displays. The new shows show the same image on multiple displays. That's bad enough, but Slideshow no longer supports nested folders (!). That's really stupid.
- Auto-correct is annoying and buggy - it causes my cursor to periodically vanish. I disabled it and I disabled auto-character substitution. i think this was causing Citrix issues. Needs to be disabled for every user.
- Spotlight activity can lockout user interaction. I've seen this in Lion too. This is bad enough to qualify as a bug.
- Sceensaver/slideshow CPU use is ridiculous. An app.net correspondent suggested they were embedding Rosetta to run PowerPC code. Seems plausible.
- So far Mountain Lion is substantially slower than Snow Leopard for many of the things I do on my 2009 machine. It's not intolerable, but I would have liked more optimizations.
- Apple has not updated the Airport Express 5.6 installer to run on Mountain Lion, it's needed to configure older devices. This is a sh*t. I used Pacifist to install the app and configure the old express I use to for music.
- Front Row is gone. I didn't notice this since I didn't use it. Still, disappointing for many.
- Many users report power issues with Snow Leopard laptops.
- It is exceedingly annoying that Save dialogs default to iCloud.
- RSS support is gone from Mail.app. I expected that and didn't use Mail RSS, but an issue for some.
- You can turn off horizontal scrolling on the Magic Mouse. Almost worth the update by itself. Two finger double tap for Mission Control is essential. Mountain Lion makes my old Magic Mouse tolerable.
- Microsoft Remote Desktop Client is not officially supported in Lion or ML (must be end-of-life)
- I thought ML was doing better than SL as a print server, but then my Brother HL-2140 printer stopped working. A search turned up a range of printer dysfunctions in ML. Truly, the CUPS experiment was a failure.