In December 2009 I installed it in Open Office and checked out a copy of Genesis that I had in Northern Sotho. This was based on one that I had scanned, OCR'd and edited about fourteen years ago (1995). It correctly picked up a number of problems where words had not been separated correctly. Unfortunately there were still a number of words that were correctly written but which it tagged as being incorrect. The problem seemed to be the system of prefixes and suffixes in Northern Sotho. It is very difficult to cover all forms of a word. In January 2010 I tried the Firefox version on the same Genesis passage which I had uploaded onto the Wikipedia ( http://incubator.wikimedia.org/w/index.php?title=Wp/nso/Modimo&action=edit ) The results seemed to be much better than the December results. This is a very useful tool to assist people when using Northern Sotho on their computers.
This review is for a previous version of the add-on (20100125).