Besides all the special cases in the normal use of Apache Groovy (e.g. definition of `==` different to Java), you also have to remember all the Jenkins-specific special cases (e.g. Groovy's collections methods don't work). I wouldn't call it simple or easy at all.
Are you sure you're not thinking of Jenkins _Pipeline_?
Jenkins _Pipeline_ definitely has these issues. Jenkins _Job DSL_ has always worked fine, including all the special collection method operations (grep, find, collect, each...)
