Designing good user interfaces to information retrieval systems is a
complex activity. The design space is large and evaluation
methodologies that go beyond the classical precision and recall
figures are not well established. In this paper we present an
evaluation of an intelligent interface that covers also the
user-system interaction and measures user's satisfaction. More
specifically, we describe an experiment that evaluates: (i) the added
value of the semi-automatic query reformulation implemented in a
prototype system; (ii) the importance of technical, terminological,
and strategic supports and (iii) the best way to provide them. The
interpretation of results leads to guidelines for the design of user
interfaces to information retrieval systems and to some observations
on the evaluation issue.