The features include:
- Smarter best guesses: Where you upload an image and Google tries to be as specific as possible. For example, you upload a picture of a flower, it tells you what type of flower it is, not that it is just a flower.
- Knowledge Graph results: Google will also now show knowledge graph results for some of the images you upload. For example, if you upload a picture of me, Google will show my knowledge graph result at the top right. Although they should be smarter and just show me, not that other Barry Schwartz.
- More comprehensive search results: When you upload a picture of an item that is trending in the news, Google will make sure to show fresher, newer and more updated content in the search results.
The one issue is, as reported at Google Web Search Help, the search by image feature doesn't work when you upload by drag an drop or by URL using IE9. Googler Albert said:
Thanks for reporting this! We're investigating the issue, and will hopefully be able to resolve it soon. In the meantime, if you'd like to do a search by image, please try doing it from an image search results page (i.e., do a search for a random query, then hit the camera icon in the search box). This should work for the time being.
Update: Two weeks later, Google fixed it.