Google Trends says Groovy is just as popular as it was 10 years ago. The number of downloads has increased significantly but it is not because of Gradle, as Gradle bundles Groovy. It is also currently placed #16. on TIOBE Index

And last, Groovy with compile static is in most cases, just as fast and memory efficient as Java.

Some people always talk down Groovy, yet the numbers speak for them self. Before Kotlin, Groovy was attacked by Scala developers.

The major thing Groovy has over both Scala and Kotlin is strong similarity to Java syntax which makes the learning curve non-existing. And that is a bigger deal than a random cryptic/confusing programming expression. Code readability is very important.