Taxi Driver is an excellent movie.  Even though some people complain that it is slow moving, it kept my attention which usually doesn't happen when I watch movies.  There was a lot of attention to small details, which was important and added a lot to the movie.  It raises some difficult questions which aren't really addressed, but that's a sign of a good movie - it gets you to think about your own thoughts and answers to the movie and the situations presented.  I think it is an excellent film.