I am a relatively recent transplant from C# to Java. I'm still getting my bearings, but my general sense is that Java has an amazing ecosystem in the large scale, and that makes it much easier to tackle the hard problems, but is the absolute pits to work with for everyday challenges. IOW, Java makes the hard problems easier and the easy problems harder.

Concrete example: .NET has nothing comparable to the Hadoop ecosystem, or to International Components for Unicode.

Concrete example: Compared to what's in .NET, a lot of stuff in the core Java libraries feels very half-baked. Streams, for example is missing a lot of useful features that I am used to seeing in every comparable library. There's not even a mapi in there. Bifurcating it from iterables and the rest of the collections API also creates some ergonomic annoyances that don't exist in, e.g., .NET or Scala's equivalents.