If Eclipse is evidence that Java is good at GUIs, I shudder to think what the output of something bad at them must be like to use.

edit: to give you a constructive response: Eclipse is an excellent illustration of how godawful Java is at GUIs. It chugs horribly on even high end hardware because of Java's interminable GC pauses getting in the way of interactive response times. It looks native nowhere, and somehow contrives to feel even more alien than it looks. It manifests platform dependent UI bugs, completely defeating every last shred of its claimed "write a GUI once, deploy it anywhere" advantages.

If you want to make the argument that Java is good for GUI's, feel free, but you just picked the two worst examples I could possibly think of. As a Mac user, the UI for Eclipse is such a huge turn-off that it soured me on Java as a whole (back before I really knew anything about Java; today, there's plenty of other stuff to dislike besides the GUI toolkit). And Minecraft? That's not a UI, that's an OpenGL game. Nothing about the custom OpenGL-based UI it presents to users says anything about Java, or has any bearing on other Java apps you might write.

"concurrent by design" != "can be concurrent / has threads"

Well, yeah, because Go is compiled, not interpreted. It's GC isn't as optimized as Java's, but for straight computational speed, it's pretty comparable to other compiled languages.

It just isn't a drop-in replacement for Java because it doesn't live in the same space. It does, however, have a similar feel as Python, especially with slices (except Go's don't copy data) and first-order functions. It's a completely different feel though than Python.