I've used IntelliJ since version 6. Now we're version 12. It's just gotten better. Version 12 is definitely an incremental release. There's nothing too whiz bang here that I care about, but the quality overall is increased.
IntelliJ 12 New Core Features
The highlights of the "What's New" list include Java 8 support, Spring tools update, Play 2.0 support, and Android UI designer. All positives, but not really things I care very deeply about and will probably never use. There's a bit more on the list, but there's nothing that is a huge, "Now IntelliJ can do ______" item.
IntelliJ 12 Quality of Life
During my evaluation, however, I have been very pleased with the quality of life it has afforded me. IntelliJ has always treated me very well in comparison to the competition. IntelliJ 12 just makes that good experience a little bit sweeter.
This has to be inspired by the rise of Sublime Text, which has a dark theme as its default. More and more devs I know are using Sublime extensively. Overall, I like the look of the Darkula theme. It's a bit easier on the eyes. The icons got a fun, retro overhaul. In some cases, I've noticed things that my eyes have grown so accustomed to that they have ignored for some time. It's also taken a bit to get used to it and start to expect things and see them faster. I find it interesting that soooo much of this release has been focused on this UI theme.
Popup Dialogs are Faster
It seems that when a non-main window is told to appear that it does so a bit quicker now. Intellisense seems a bit more snappy, and the "recent files" switcher doesn't lag as it seemed to in the past sometimes. It's fun, and it lets me go faster.
Better OSX Shortcuts
When I switched to OSX from Linux, I was immediately disappointed by the lack of keyboard shortcuts in comparison to Linux. The most egregious omission was the lack of alt-* combos to press buttons in the UI via the keyboard. Alt-p to engage the 'push' button in the Git push dialog has been a long time coming.
Git Integration is better
For performance and UI reasons, I would often just use Git on the command line instead of from within IntelliJ. Now the Git integration is better than ever. It seems waaaay fast. I'm a little puzzled at how the git push could be so much faster in comparison to the previous version.
Project Type Support
Small thing, but I like the new "New Project" dialog. It's simplified and easier to navigate. It is fast and simple. It doesn't take you through options that don't apply. I'm in that dialog a lot, and I like the change.
The Right Direction
Really, there's not a ton new here. It's such a solid tool to start. It's where I spend most of my day though, so even incremental quality improvement is welcome.
Let's see, what's not there that I wish for?:
Run and debug Grunt and other Node-based cli apps
Does IntelliJ already do those things? Probably, and I just don't yet know how to bend it to my will.