Something that I think the Barbican does well, and The National Theatre (another London brutalist building) also does well, is interesting interior spaces - openess, multi-levels, "floating" staircases, interior views, visible structural elements etc. I find both of these spaces energising and interesting to be in.
Other brutalist buildings are just horid. I worked in Sampson House (just behind Tate Modern) for a couple of years which is also brutalist but the interior is dank corridors and dingy spaces. I also worked at the brutalist IBM offices next door to the National Theatre and it was also a souless space inside. They have absolutely zero-ambition and are the polar opposite of the spaces at the Barbican and National Theatre.
Other brutalist buildings are just horid. I worked in Sampson House (just behind Tate Modern) for a couple of years which is also brutalist but the interior is dank corridors and dingy spaces. I also worked at the brutalist IBM offices next door to the National Theatre and it was also a souless space inside. They have absolutely zero-ambition and are the polar opposite of the spaces at the Barbican and National Theatre.