I'm using Netbeans at work now, on a Mac, and the experience has been considerably less than ideal. The UI is almost, but not quite Mac-like (to be fair, when I've used it on Windows, the UI was almost-but-not-quite Windows-like) and I keep running up against things that seem like they should be configurable but are not.
It's like Netbeans was designed by people who had UIs described to them, then semi-randomly decided that was stupid and they could implement them better without doing any research about why those things were the way they were.
It works. It doesn't suck as much as it could. That's about the best I can say about it.
Not-quite-Mac-like is way worse than not-at-all-Mac-like.
Look at Sublime and Atom. Completely customizable and identical across platforms. I'd prefer that level of honesty to the fake-Mac interfaces that try and fail to look native.
I love NetBeans on Windows, but it's terrible on Mac if you're a Dvorak typist and you want to use keyboard shortcuts. For some reason, when using the Dvorak layout, NetBeans can't decide whether to interpret a key press as Dvorak or QWERTY when using shortcuts, and often it uses both. For example, the W key in QWERTY is a comma in Dvorak. If you press Cmd-, to invoke the Preferences dialog, it interprets this as both Cmd-, and Cmd-W, so it brings up the Preferences dialog and closes the current file.
IntelliJ has very good IDEs. But their IDEs would be even better were they native OS X applications. For example, you can't use the Mac OS X services like "Look up in a dictionary" in IntelliJ.
For me, it's the open and save dialogs that bother me most. I quite like the editor, especially as compared to Eclipse, but for source editing, I'd rather use one the OS X editors like TextMate or BBEdit.
Sublime is the best cross-platform app I've ever used. I can count on one finger the number of times I've used something that felt native on more than one platform.