If your company has existing Struts 1 apps that are working fine, I wouldn't bother upgrading to Struts 2. For new development, I think Struts 2 should get a serious look as it expands on the same fundamentals as Struts 1 but at the same time incorporating many lessons learned from production deployments and features from other frameworks.
In addition to the obviously excellent Struts 2 in Action book, I recommend taking a look at the Struts 2 migration guides, particularly the tutorials by Ted Husted and Ian Roughley:
http://struts.apache.org/2.x/docs/migration-guide.html