Here is the official change log from Google:
Improved scrolling performance
Increased responsiveness to pinch-zooming on pages
Audio now continues to play while Chrome is in the background. Audio playing in Chrome will now pause when the phone is in use. This requires an additional permission
Expanded support for HTML5 features
Improved text font clarity and stability fixes
We also ran the SunSpider and BrowserMark 2 benchmarks on the Sony Xperia Z to see what kind of performance boost the new Chrome brings. On the SunSpider test the new browser scored 1306ms, compared to the old 1908ms results (that’s a huge 31% performance bump).
Lower is better
Sony Xperia Z (new Chrome) 1336
Sony Xperia Z (old Chrome) 1908
On the BrowserMark 2 benchmark the new Chrome running on a Xperia Z unit did 2093 points, while the older version of the browser scored 1865. This means the performance has increased by 12%.
Higher is better
Sony Xperia Z (new Chrome) 2093
Sony Xperia Z (old Chrome) 1865
We suggest everyone who’s using Chrome to get this update as soon as possible. It’s definitely worth it.