Ernest reviewed Programming Groovy: Dynamic Productivity for the Java Developer by Venkat Subramaniam and gave it 7 out of 10 horseshoes.

This is a reasonable, if informal, introduction to the Groovy language. Although I haven't had the opportunity to do much with Groovy myself, I suspect that this book wouldn't help if I painted myself into a newbie's corner; I would want a more detailed language guide to refer to. [...] I wanted a description of the Groovy language itself, rather than repeated assurances that it's "just like Java" interspersed with multiple demonstrations of the ways in which it's more assuredly not.

You can read the full review and discuss it here.