Last night I attempted to fresh install OS X Mountain Lion on a new hard drive. Doing a hard drive install on a Mac is much easier if you have iFixit’s 54-bit driver kit. It has all the bits you need to remove the bottom cover the of MacBook Pro and the torx bits to transfer the hard drive mounting screws.
It took a lot of research to determine the best and proper way to install Mountain Lion. Unlike older versions of the operating system Apple does not provide physical media. After replacing the internal hard drive with a new blank one, I used an adapter to boot the recovery hd on the old hard drive via USB. You can do this by holding the option key while the system boots. It will give you a list of valid hard drives to boot from and so you just choose the recovery hd. Owners of modern macs can also hold command+r in order to do an internet boot. Once you boot the recovery system you should then choose the standard Mountain Lion install to the new hard drive. It will take a long time to download. About two and a half hours for me. However it is critical you choose this option over simply restoring from a time machine backup or cloning your old drive if you want your new drive to have the recovery hd partition to enable the Find My Mac and FileVault encryption features.
Before I was aware of the recovery hd issue I started restoring from a time machine backup and then stopped. This did not cause any adverse effects. When I did the fresh install after restoring about 10% of my time machine backup, the computer booted without issue. The apps that had been transferred were still present. I used the migration assistant to finish restoring the time machine backup after verifying my system worked.
Others have already reviewed Mountain Lion to death so I’m just going to share a couple thoughts. The first is that for the longest time my iPhoto application was importing photos taken on my iPhone 4S as blanks. Trips the Apple Store and use of the iPhoto library manager did not fix this issue. The fresh install plus time machine restore appears to have remedied this. The second issue I’ve noticed is that when accessing the external firewire hard drive the computer slows down when it spins up. This issue persists into Mountain Lion. It is disappointing Apple has not addressed it.
When upgrading to Mountain Lion the computer will prompt you about any software that is incompatible. The only software that was not compatible for me was Parallels 6, but the author offers a paid upgrade that is compatible. With the advent of the App Store paid upgrades have been less common so I find it irritating when I have to pay. However the software developers have to eat.