7+ years of Java/JEE/Spring
3+ years of ServiceMix/Camel/EIP
1 year of Grails/JQuery/FE
Integration middleware and frontend architect at work, startup and Grails enthusiast after hours.
Much simpler than JEE but sometimes could have but even simpler and yet more lightweight itself.
Quite easy to learn (but e.g. Sammy.js is a bit easier) and powerful JS framework. The syntax of directives and filters might be not intuitive at first. The "content replace" effect is kind of annoying. But in general, it helps you write good quality code in both scripts and views of your frontend application.
Grails is the top MVC framework for the JVM. Groovy is extremely powerful, together with hot-deployment making development really productive.
The 2.0 version adds some cool features, e.g. where queries and more interactive console.
The few drawback include: lack of built-in ui framework and some undocumented features. The well integrated Spock unit test framework helps to avoid common bugs from dynamic typed language like Groovy.
Open Source version of Liferay is maybe fun to use, but really pain to deploy and develop. The Portlet API is too complicated and doesn't fit modern websites nor applications. Some solutions include using another framework for portlet implementation, e.g. grails-portlets plugin form Grails, but this introduces another problems: session sharing and authentication.... Web contents and ability to override every single default jsp page are great features, but you should expect more from mature CMS for Java. Community and documentation exist, but not very helpful in everyday use :( Enterprise version could be a better choice.
Best Java IDE. Open source version lacks some frameworks support (Grails!) but still better then Eclipse/Netbeans.
Struggling from BPEL problems: imperative, XML-based and too complex. Not scalable (no clustering). The good are: activity recovery and process flow stored in DB - for debugging.
Great and clean syntax.
As Shay Bannon said - using pure Lucene is challenging. Simple issues - date and empty fields storing, exact queries - can be very harmful. I'd rather use some wrapper framework like Elasticsearch or Solr (unless need to embed search component in an existing application).
Great and helpful API, missing some docs, which are hardly navigable.
Good and simple to use ORM. But mixing XML, Java and SQL in one mapping file.... This does not end up with clean code :)
Really powerful and feature complete. May be not intuitive at first glance.