Unity 5.0 Beta 18
Improvement

Profiler: Stop collecting GPU data when GPU Profiler chart is closed
Profiler: Stop collecting profiler's data on Player's side if recording is disabled
Timeline Profiler: Add proper detailed names to Physics Jobs and prefix the names with "PhysX".
 Fixes

2D: Sprite Packer page list is now refreshed after packing.
2D: Sprite importer multiediting now works for packing tag, pixels per unit and extrude fields
2D: Sprite name can't be empty, or contain characters that are not supported in assets when created from Sprite Editor
2D: Hotkey for sprite Trim 'T' doesn't intervene with sprites naming anymore
Editor: Animation Window Add Property button not hiding for new project
Editor: Fixed null exceptions from Animation Window when opening projects
Editor: Shadows working correctly when zoomed in animation preview window
Editor: Fix exception when clicking "Add Behaviour" button
Editor: Remove unsupported OSX menu items (Start Dictation & Special Characters)
Windows Store Apps: fix building Universal apps in batch mode
Serialization: Added ability to do automatic fix of invalid references to scripts in scene file (to valid registered scripts)
Serialization: Fixed windows Layout loading if script for previously opened custom window is absent
Windows Phone/Windows Store Apps: Gyroscope.gravity returns same values as other platforms. It used to be inverted before.
Windows Phone 8: Camera.ViewportToWorldPoint returns correct value in orthographic view.
Shaders: Fixed legacy Diffuse Detail shader when in linear color space.
Windows: Windows 10 reports SystemInfo.operatingSystem string properly.
Graphics: Fixed "Tiled GPU perf. warning" in editor resulting in poor performance.
Shaders: Fixed "Maximum number of shader keywords" error in editor resulting in really bad build-time performance.
ParticleSystem: Fixed regression from Beta 17: Broke editor update of selected particle system.
Editor: Reduce serialization depth limit warnings
Scripting: Fix crash when calling DestroyImmediate in MonoBehaviour constructor
Editor: Fix crash when executing a menu item from a static constructor
Editor: Remove spurious "Platform modules already initialized" messsage when upgrading projects
Linux: Trim device identifier
Installers: Download Assistant on Mac doesn't ask for credentials again after downloading has completed
 Known Issues

On Windows 7, system dialog (File Open/File save) and homescreen/project launcher window, the editor in the background doesn't redraw properly when the window is dragged around
Legacy Light Probes baked coefficients doesn't get upgraded to the new data format, probe coefficient data will be incorrect. New Light Probe Groups will behave correctly.
Upgrade guide

 The following are changes and fixes to 5.0 features and regressions...

 Change

Shaders: Renamed UV1/UV2 in Standard shader detail UV selection to UV0/UV1.
Editor: UI improvements to Standard shader emissive color/texture/intensity fields.
Improvement

Plugins: Added default settings for plugins located in:
Editor\x86
Editor\x86_64
WSA\SDK80
WSA\SDK81
WSA\PhoneSDK81
WSA\UniversalSDK81
Check Plugin Inspector documentation for more info
Plugins: Only relevant Standalone plugin settings will be shown. For ex., OSX and Linux options won't be shown for native dll, because it cannot be used on those platforms
Plugins: Added warning box for native plugins in plugin inspector, once native plugin is loaded by scripts, it cannot be unloaded until Unity is restarted.
ReflectionProbes: Added QualitySettings.maxRealtimeReflectionBounces, this limits reflection bounces for realtime reflection probes.
ReflectionProbes: When baking Custom probe, game object's name will be appended to the filename
ReflectionProbes: When manually entering position values in the Transform inspector while in Box editing mode, the box will not move.
ReflectionProbes: You can now set bake resolution for default reflection, it can be found in Lightmapping window
TerrainCollider: Removed warning about TerranCollider no longer supports being a trigger from get_isTrigger
Editor: Fixed undoing changes to light probe group
Shaders: Added "keepalpha" surface shader directive to not force 1.0 to alpha channel for opaque objects.
Deferred Shading: Standard shader outputs occlusion texture into diffuse g-buffer alpha channel.
Documentation: Added documentation for "Optimizing Shader Load Time" and "WebGL Networking" plus lots of improvements and fixes in general
API Updater: Introduced UnityAPICompatibilityVersionAttribute to allow updater to avoid checking assemblies already updated to / compatible with current Unity API.
GI: Exposed modelling tolerance to lightmap parameters. This parameter allows setting the maximum size gap to be ignored by GI calculations.
GI: Clamp AO distance to zero in UI. AO distance of zero means infinite length rays as it did in beast.
GI: Added a baked lightmap tag. This can be used to force instances into specific baked lightmaps.
Fixes

Editor: Fixed wrong color for editor progress bar in dark skin
Editor: Fixed repaint issue on Win7 for windows under modal windows
Editor: Recently used projects list now has separate keyboard selection and mouse hover again (hover changing selection was making "enter to reopen" unpredictable)
Editor: Fix Windows repaint issues with windows behind modal windows on Win7
Editor: Fix that undoing when creating assets would cause the temporary asset state to not be cleared
Editor: Fix ctrl+click as context click for audio mixer groups
ReflectionProbes: When baking probes, Unity will no longer bake shadows from objects which are not marked as ReflectionProbeStatic
ReflectionProbes: Fixed a bug, where Unity would sometimes not rebake probes or default reflection, when material has a different cubemap setup.
Plugins: Unity will correctly load native plugins from script even if the letter case won't match like it was in 4.x, for ex., if you write DllImport("plugin"), but on disk it's Plugin.dll (with upper case).
Plugins: Fixed a rare crash when calling into native plugin from finalizer thread.
Shaders: Fixed Sprites/Diffuse shader not handling transparency properly.
Shaders: Fixed Standard shader using wrong texture scale/offset value.
Shaders: Fixed Standard shader wrongly falling back to VertexLit when lower shader LOD is set.
Shaders: Fixed exceeding maximum shader keywords sometimes resulting in crashes.
Metal: Fixed some shaders not compiling properly (if they change global variables from inside of the shader).
Reflection Probes: Realtime probes more efficient on mobile GPUs (less framebuffer restores).
Graphics: Texture2D.SetPixel and friends work with floating point texture formats (TextureFormat.RGBAFloat etc.) now.
Graphics: Floating point texture formats (TextureFormat.RGBAFloat etc.) work on D3D9 now.
Editor: Don't show "Fix now" button for legacy cubemaps in shader UI, fixes crash.
Editor: Fixed emissive Standard materials getting same emission color when multi-edited.
Editor: Fixed semaphore issue on OSX
iOS: Fixed allocator assert when doing skinning
API Updater: After being updated, some assemblies fails PEVerify with message "[MD]: An attempt was made to load a program with an incorrect format."
GI: Fix issue with too high intensity GI in the players.
GI: Fix issue with lightprobes when baked multiple time in non-continuous mode.
GI: Make sure GI has converged before issuing reflection probe jobs.
GI: Fix skybox appearing very dark in gamma rendering mode.
GI: Fix for creating lightmap data assets larger than 4GB.
GI: Fix spurious errors when converting area lights for GI.