Good article but it misses a key point: Calligra Words can open .doc and .docx files, but *cannot* save to them. This is presumably due to the focus on Calligra as a /viewer/ for mobile devices, but is a show stopper for a vast majority of real-word word processor use cases which require round trips to MS Word. (MS Word support for ODF is not sufficient for this).
It would also seem that Calligra lacks support for "track changes". Combined, these two gaps make it a far less viable alternative to LO than projects like AbiWord.