One of my favorite movies and one of Robin Williams's best. I won't say that it's his greatest performance (see Mork & Mindy or Mrs. Doubt fire), but it's a very enjoyable film that hits just enough beats for most people to sit down and enjoy themselves. And maybe even have a discussion on what it means to be alive.
The only thing negative I would mention about the movie is that occasionally it may start to drag, or feel long to some people. I mean it is a 2+hr movie about robo-Robin searching for his place in a world of humans. So if Sci-fi isn't your thing, or if you don't like Robin williams, this might not be your movie.