I have used various versions of Adobe InDesign for 10 years. When I first starting using it, QuarkXPress owned the bulk of the market, but these days InDesign is the industry standard.
Most of the new features are geared towards the production of electronic documents and management of content across multiple documents. InDesign is the best software available in its field but is it worth the upgrade?
When starting a new job for an existing client you can open previous jobs and drag all the elements you might use into the collector window. In the previous version, I would just cut and paste from old documents but this is a nice tidy feature.
I like the Place and Link feature a lot. You can now have parent and child text. The parent is like a master text that is used in multiple documents. If you need to make a change, you change it in the parent and all the instances (the children) of that text will update next time they are opened. You can also link the style used and changes made to that style will be applied to children texts and objects.