5 emails arrived on my mailbox. 1 of them has the password and 4 of them has a pdf attachment. So the password worked only on 1 pdf.
Open the Mac App Store and click on Redeem.
Download the Mountain Lion. File is more than 4GB. So if you have slow internet connection, it might take awhile. I don't know if Apple provide a USB or a CD copy of it. But for sure if you have a slow connection, you can always bring your Mac to the Apple store to download and install the new OS.
Installation took more than 45 minutes for me. I don't see much change on speed or battery life on my Mac after upgrading. (probably because my Mac is always connected to a power supply and I rarely turn it off)
I love Messages app. I can now use my mac to send messages to my friends who have iOS devices. And it is sync with my iphone and ipad! Dictation is kinda cool too! And the other new features... I didn't bother to check and use it as of now. Even the notification is not yet set. Kinda busy watching Olympics! :D






