Is Grails now worth it vs Ruby or other roll your own?
Of course, the answer is not 'Yes' or 'No' but it depends. It depends on your requirements (do you need to be in the Java World?), on your preferences as well (do you prefer the domain-oriented development, do you prefer Groovy...)?
However, I can answer that Grails is a serious alternative to Rails. I believe that whatever is your Rails application, you can do it with Grails as well. But depending on the nature of your project, it might take more or less time. Again, if you are familiar with Rails but not with Grails, Rails is the safer option.
Yes. If you take a look at my initial messages (in this website or others), I was complaining a lot about Grails bugs. But, you just need to remember that Grails is a little rough on the edge (not too much use of domain inheritance ,for instance) and once you are familiar with the framework, you don't experience too much bad surprises. I am not saying that Grails is not buggy. It is certainly more than Rails. But also, it is more usable than buggy. A piece of advice for that : use as few plugins as possible. Because many of them are buggy and some are not compatible among themselves. So, do not include grails plugin unless you are sure that the grails plugin is up-to-date, non-intrusive and tested (by yourself).
Yes. You almost do not need to deal with DB design. Configuration is almost done for you from the beginning thanks to Convention over Configuration. Your application is easily maintenable. The only drawback I see is front-end development that is not as rich as other technologies (like Rails or ASP)
I cannot say because I still didn't go my website live but I am pretty confident since sky.com is using Grails and the sites attract significant traffic - around
7 million page views per day . Again performance depends a lot on your application architecture and design decisions.
Is the Eclipse plug-in better than it was and fit for purpose?
No idea. I am using IntelliJ but I guess it is not much better than one year ago according to complaining messages I see on the Grails realm.
I second the point about the plugins. You have no guarantee that plugins will be updated for newer versions of Grails. I would recommend that you stick with those backed by Grails / SpringSource.
Plugins are an interesting bunch in the grails community. If you look at plugins as black box that you use with your app, then I think you are going to have problems. But if you look at plugins as templates that the grails community has provided you will get along much better.
NetBeans or IntelliJ are the IDEs of choice for Grails. IntelliJ if you have the money.
Rails for 5 years, Groovy/Grails for 8 months. Familiarity says Rails is better, but Grails is eminently usable once you're over the initial learning hump. Grails feels a little config file happy in comparison (do I really need 6 or 7 for a single plugin module?), but the persistence layer is very nice to work with. As for IDEs, used STS for 4 months with many frustrations, then tried IntelliJ for 4 days, and never looked back.