While the 2013 Catalyst Linux driver updates weren't too great, on the open-source side the AMD Linux driver work was fantastic! AMD's open-source driver improvements in 2013 were splendid. Users of AMD's open-source Linux GPU driver saw Dynamic Power Management support and open-source UVD video acceleration as two of the biggest open-source AMD accomplishments of 2013.
On the open-source AMD driver side there were many performance improvements to the point that for older Radeon GPUs the performance can be sort of comparable to Catalyst. For the Radeon HD 7000 series and newer, the RadeonSI Gallium3D performance is improving and advanced a lot in 2013, but is still not yet at parity to the older R600 Gallium3D driver.