The station is a beautiful structure.
The interior plaza includes a tropical garden that is warm all year round. A relatively peaceful place to rest while waiting for your train to depart.
Access to the suburban trains (Cercanias).
Trains come and go pretty regularly.
I stopped by the monument to the victims of the 2004 Train Bombings. A very quiet place to thing amongst all that never-ending flood of people that circulate through this station. You can read more about what happened here at Wikipedia.