The collection is not very large, but worth the visit. From the history of Miro to some of his iconic pantings, this place is a great destination in Barcelona. For me, however, the highlight has always been the Calder fountain in memory of the miners that does not run on water, but mercury. Not only gorgeous to look at, but very impactful. Views of the city from the surroundings are great, too.
Pro tip: Go early in the morning before the school groups. Otherwise you will find yourself in a zoo of teenagers counting the minutes to get out of there and acting accordingly.