When you locate a document in the Special Collection you are interested in, you can pay as you go for the article or set up an account. It's just a guess, but I believe OpenText's search engine is really an adveritisment for its commerical document storage and retrieval software. Like a number of the other services, OpenText's interface in entirely menu-driven. It consists of a number of blank fields surrounded by qualifiers. It is obvious from this description that OpenText is strong on phrase searching and the proximity of words.
Field searching is a bit weak.
While the searching syntax is a bit obtuse, it is the most powerful and when used correctly can provide result sets that are easy to manage. Like a growing number of search engines, AltaVista employs statistical methods for refining the results of queries. This method is similar to Verity's services as well as North Light Search. If you like AltaVista, then buy the book AltaVista Search Revolution and you will like it even more. The strength of this service lies in its Internet reviews.