I don't have much experience with groovy and grails but I like the way you can create controllers etc. in grails on command line. I was looking at spring roo but it looks to me that it is easier to create lets say entity, controller etc. then learning/remembering all the command line arguments. In other words, Roo has too many options and seems to be quite steep learning curve (as I said, I'm not grails neither roo experiences user, but grails seems to be easier/better)
What is your (unbiased) opinion?
First of all, you don't need to remember Spring Roo commands and arguments. The Chapter 1 of Spring Roo 1.1 Cookbook which is available for free shows how you can use TAB-based auto-completion feature of Spring Roo to discover the commands and it's arguments. I don't see that there is a steep learning curve in Spring Roo. All you need is some understanding of AspectJ ITDs, good understanding of Spring and how Maven plugins are used. I have used Spring Roo over a period of one year now, and I'm quite happy with it.
In my opinion, most developers think of a RAD tool as a GUI based drag and drop application. After using Spring Roo for a while, you'll realize that it is very user friendly tool and may be using command-line driven shell is better than using a GUI based application