The metro is both a cheap and easy way to get around in Barcelona. Compared to many other places, the Barcelona metro is also very clean and feels safe.
It is extremely convenient to get around Barcelona using the underground network. Many of the places of interest are within walking distance of metro stations.
the metro and busses are the best to move from one to another place in Barcelona. Most of the touristic places are also easy to visit them walking.
The subway system is clean, efficient, and very easy to use. Though not extensive, it covers most of the areas that a tourist would go to.