So far, as part of the Sonar Platinum membership, the new features and content that I have received are:
Command Center
FX Stacking
Recycle/Pin Plugin Windows
Expandable Send
Pattern Tool
16 Virtual Custom Amps
Addictive Drums 2
"Stunning" New FX Chains
Mix Recall
The New Control Bar
REmatrix Solo
VocalSync
Craig Anderton VoxTools
Craig Anderton Acoustic Piezo CA-X Amp Sim
Hardgroove Steinberger Rapture Expansion Pack
Hardgroove’s Bass Loop Library
Craig Anderton Acoustic Guitar Presets
ProChannel module from Boz Digital Labs-Bark of Dog
ProChannel module from Boz Digital Labs-Panipulator
New Impulse Responses for REmatrix Solo
Anderton Collection “Phasor Constructor”
Les Paul Gold Top Expansion Pack-DimPro
Onscreen Virtual Controller
Pedalboard FX Chains
Kickmaster FX Chain
Synthetic IRs for REmatrix Solo
Kick Start Pack
SizzleBus
Drum Replacer
Strum Session 2
Deflate Gate
EDM Percussion Loops
Plug-In Upsampling
Relative Video Path
Windows 10 Compatibility
Interactive Project Tutorials
Showcase Templates
Mixing Templates
Mastering Templates
Start Screen
.PNG Support
Export Presets
Enhanced Clip Export
Synth Recording
Style Dials x3
Upsample on Playback
Aux Tracks
Patch Points
Rapture Session
Monitorizer FZ Chain.
I may have missed a few.
This does not include the hundreds of fixes and optimisations..
Do I think it is worth another year? Err, yes.
I have upgraded every time since the X series, and every few times since Sonar 6.
I seem to be getting more in a year, and a greater level of bug fixes than with the old model..
edited to add clarity