Cons:
Map editor is clunky. I want to drag and drop topics to reorder them, not use arrow buttons. (This applies to version 5.1)
The code view needs a pretty print option. It’s very difficult to read the code.
You can set up certain parameters to format the output (like headers/footers and CSS or parser used), but these parameters don’t appear to be documented. If they ARE documented, the documentation should be easier to find.
Implementing your own modified DITA Open Toolkit (DITA OT) could be easier. You have to layer your changes over XMetaL’s DITA OT files instead of just pointing the program to your own DITA OT folder. This makes updating the DITA OT inconvenient.

What I like most about FrameMaker is how easy it is to create multi-purposed content from one linear content source. The approach is old-school; author content in chapters or blocks of related information, using headings to break the content up – a practice that is as old as book writing itself. But, it is very easy to leverage this approach to authoring well-chunked topic-based content as well.

The trick to making this seemingly linear authoring tool work in a single-source fashion is to make smart use of the many dynamic functions it provides. By leveraging multiple master pages, conditional text, variables, cross-references, and reference page elements, you can set up your content to work as a book, a Help system, a user guide, a training guide, or have it ready for multiple language translation.

FrameMaker isn’t known as the most cutting edge or technically sexy tool out there, but the old saying holds true: if it ain’t broke, don’t fix it. I’ve been successful with FrameMaker for over a decade, and don’t see its usefulness disappearing any time soon.

Thanks