Java is a great language, and the JVM a great platform. I think that the thing which makes Java underrated isn't the language, but rather Java Developers. There are tons of great Java developers, but they are probably great developers in any language. But Java being the language of choice at so many enterprises results in a large number of very low skilled and inadequate Java programmers, who would be bad developers in any language, but specialize in Java.

I have mixed feelings about Java. It's a solid feature set, and I really love how InterruptedException was always a thing, so you can generally terminate a thread and it works (a lot of languages don't do this right). I love checked exceptions.

But the spooky action at a distance type annotation hell, needing builders everywhere because of lack of named parameters, poorly conceived generics, nullability not being first class, lambdas being incompatible with checked exceptions, etc. are a pain.