Python support in Intellij Ultimate is also "just a plug-in". Adding the plug-in gives equivalent functionality to running the stand-alone PyCharm.

Apart from that, the support for Scala is not at the same level as the support for Java. Given the differences in language complexity, it is much easier writing tools handling Java code than writing tools for handling Scala code. Combined with the scale of markets, I would be very surprised if Scala support was even near Java support.

With that said, I can't get Scala to run in my IntelliJ 14 install, so I'll have to stay in 13 for now. Sigh...

It is a plugin, but it is a Jetbrains made plugin, so it's not as if it's lacking in support. The upgrades in this version are enormous: The debugger in 13 was only semi-usable because it's pretty hard to write any interesting debugging expressions in Scala without using a lambda, and lambdas were completely unsupported in 13. It's not quite the Java debugger, but I'll take it.

I have yet to try if their SBT support has improved as much as it should: The old SBT import worked if your project was simple, so it worked for all the toy projects I have, but it always failed on anything serious I did for work.

The Scala plugin lags behind the Java support a little (I'd love to have the new annotated code feature that Java has in Scala), but IMO, it sure beats doing the same work in eclipse, or in an editor that doesn't understand the language at all.

I'm ok with that. They have a lot of stuff available as plugins. Even as a Scala user, I'd rather they pushed more stuff out into plugins to make the core smaller.

Further, integrating it ties is to the main release cycle. If it's a plugin, they can rev it faster. And I'd hope that they're revving it faster; their Scala support is good, but they could do a lot more with it. In particular, I'd love to see better automated refactorings; when working in Scala I'm envious of all the Java refactorings.

Full agree on the C# support. VS+ReSharper is nice but it's become a bloated blob of triple keyboard shortcut assignments and sloppy performance. It really needs some healthy competition.

MonoDevelop is surprisingly good, but IDEA is simply an order of magnitude better. With Roslyn out there, it should be strictly less work to make an IDEA for C# than it is for, say, Python, right?

They should just include the Scala plugin by default. It's the most popular plugin by a very wide margin.

Python support is a plug-in and I haven't noticed any deficiencies between it and PyCharm.