In May 2000 I gave a talk about Mizar at the Proof Tool Day in Ghent. The title of the talk was "Mizar, a not very well known proof tool", and its abstract was:
The Mizar system from Poland is mentioned often, but not many people know it from first hand experience. It is special in the sense that it uses declarative proofs, in contrast to the procedural proofs of most other proof tools. A short overview of the history of proof checking will be followed by an introduction to the Mizar system, and an assessment of its strengths and weaknesses.