Every things is configurable and each component is in perfect isolation with other. If implemented properly - this is the best framework.

....................................................................................................................................................................

0. Can use any existed java library. 1. Groovy 's advantage (than java): (0) Metaprogramming (1) more efficient operators ( Elvis operator, Safe navigation operator etc. ) (2) more useful method to JDK classes ( such as Collection#find()), more (3) can use much DSL ( can do same things with less code) 2. GORM is the bettern than using mybatis/hibernate in java app development. 3. easy to conver between map,list and json,xml. 4. Gsp is better than jsp——but I more intend not to use both at all. Instead, Grails app should response json data only. Html page can be developed by another app (using sass, angularJs, gulpjs etc), using ajax or jsonp to access json data.