I've been using docx4j, specifically the pptx4j part, for a few days now, and it has been pretty impressive so far.
I wish I could remember the exact problem, but something was omitted from the 2.6 release, and was quickly patched. (I can go back and try to reproduce the situation, if that is important). PowerPoint manipulation was not working for me (or anyone?) before the patch, but the patch fixed the problem. That's good...
The downside is that I have been having to use a nightly build, so that the patch is included. Now that I am approaching a delivery into production, my SCM people are balking at my use of a nightly build of any software in production code. Is there an easy solution for this? Or is 2.7 coming soon?
(Like I said, if it's important, I can go back and find the patch--I think it was within a couple of days after 2.6 was released in November).