The main improvement is that you can now write and overlap your writing on smartphone screens. One of the biggest issues with writing on a smartphone is that you often run out of space for your query. Now, when you run out of space, just continue on by writing over what you've written before.
Google also has improved the ability for similar characters. Now you can easily correct characters that look the same (like "1" and a lowercase "L").
Finally, Google improved their Chinese character system.
Forum discussion at Google+.