It separated commercial banking from investment banking. It made the U.S. Banking system more like the European Banking system. (Our banks are not yet European banks which provide all financial services, but they do have closer relationships with investing firms than was permitted before Graham-Leach-Bliley)
Honestly, I have a much larger problem with the Riegle-Neal Interstate Bank and Branching Efficiency Act.
The interstate branching that is allowed created the mega-national banks we have now. However, that isn't really my problem. (I like having the same bank everywhere I go... at least in the South)
My problem is the requirement that every bank that wants to open a new branch must have a review under the Community Reinvestment Act.
We'd have been FAR better off with the more, smaller banks and no CRA teeth than we are with massive banks under the thumb of regulators.
