Today Opera 12 has been released. See What’s new in Opera for an overview of new features.
What I want to highlight is Opera 12 has 64 bit version on Windows. To download 64 bit version of Opera, go to download page and click More options, and select 64 bit in Architecture. Then click Download Opera.
By default, 64 bit version of Opera installs into
Opera x64 folder. In this case, it would create a new profile. If you want to keep your current user profile with all settings that you used with the previous 32 bit version, you have to install Opera into Opera folder.
How to install 64 bit Opera 12 and keep its settings
Click Options to change the install path.
Edit Install path so that it installs into C:\Program Files\Opera instead of C:\Program Files\Opera x64.
Change other options, if you like.
I faced this issue myself where 64 bit Opera did not keep its settings from the previous 32 bit version. I used this forum post to solve it.
More details are available in How do I upgrade to 64-bit Opera 12 (and keep all my 32-bit 11.64 settings)?