If language is carefully used, good hits result. Hard to customize, and it needed lots of customization. When I had trouble with customization, there was no where to turn for help. No one knew how to do it or who to call that might. Key word occurence navigation is clumsy.
Document comparison is clumsy.
It's been hard to configure Webinator to produce relevant results for users. People don't understand how to do natural language queries, bad PDFs can corrupt the entire index. No problems with administration. Easy to do, fast to crawl. The survey was designed, analyzed and reported by Avi Rappoport.