I'm not really much of a movie "critic"; In fact I dislike most critics as they think everyone else should have the same tastes in movies and plays.  In my personal opinion, Taxi Driver MUST be one of the best, if not the best, movies of all time.  If you are looking for an Action Jackson, kill'em all, special effects, light-speed space travel thriller then... You will be disappointed.  However, if you enjoy thought-provoking stories, solid, convincing acting, and a movie that seriously makes you THINK and entertain you at the same time, Taxi Driver is the spot!  Then again, thats just my personal opinion :)