Firstly they have changed how the home panel looked like, though they also have clean tabs but this time the tabs are looking more prominent, further it's a drop down menu which declutter the whole space.It gives the due space that was required in it.
Secondly they have improved the section of "photos", it has more sub sections in it, further it lets you visit the most prominent of your photos at one go. Though google is also saying it will provide a better quality for the images in this they would be direct competition with the facebook, where people are really comfortable in sharing their pictures.
Another important change is with the google hangout, you can directly connect with hangout with a button at top right hand side.Now you can check which circles are enabled for hangout and change the settings as required. Though group chat facility was already present in it for long now.
Have great time hanging out.