Valve have released a relatively large update, with significant visual improvements to Cache and Nuke. Full patch notes can be seen below: 

[MISC]
– Fixed possible remote code execution bug in KeyValues parsing. Thanks to xPaw for finding and reporting the issue!
– Fixed a bug allowing community servers to override certain game files.
– Added support in vbsp for clip brush textures with different material types.
– Added CS:GO in-game blog localization for Finnish.
– Significantly reduced holiday cheer.
– Added convars cl_weapon_debug_show_accuracy and cl_weapon_debug_show_accuracy_duration
— With “cl_weapon_debug_show_accuracy 1,” when a shot is fired, a 12 inch circle will be drawn at the Effective Range of the weapon, i.e, the farthest distance at which the shot is guaranteed to fall within a 12 inch circle.
— With “cl_weapon_debug_show_accuracy 2,” when a shot is fired, a circle will be drawn at the surface that is aimed at showing the area that could have been hit by the bullet given its inaccuracy.
— cl_weapon_debug_show_accuracy_duration ( default 10 ) determines how long the debug circles last.
— The further the shot is into the spray sequence, the more red the circle will be.
[AUDIO]
– Increased radius of c4 disarm sound
– Fixed some cases where alt-tabbing away and back to the game would cause incorrect sounds to play
[MAPS]
Cache
— Visibility improvements based on color-blind player feedback
— Texture improvements
— New vent models
— Added subtle markers for grenade throws (thanks James Bardolph)
— Added plant-zone decals to Bombsite B
— Added graphic for “Sun-room” (thanks Thurnip)
— Fixed fade distance on crate in checkers
— Fixed weapons being irretrievable under vent
— Fixed all known bomb-stuck spots
— Fixed an exploit involving flashbangs from mid into checkers
— Fixed pixelwalks at mid, T-Spawn, A main, A site
— Improved .nav mesh (thanks p_NM)
Nuke
— Improved accuracy of grenade clips on metal containers
— Clip brushes now play the correct material type footstep sound
— Performance optimizations
— Removed crate stack from CT side
— Removed railings outside HUT
— Removed railings at top of Heaven ladder
— Lowered ambient soundscape volumes
— Door opening and closing predictability fixed
— Improved .nav mesh (thanks Bez)
— Fixed +use interaction through tool or clip brushes
— Fixed double doors being blocked by their sibling door being blocked by the player