Google Maps Beta is getting location reviews in lists, so when you open up the application and look at your lists of places you've been to, you should be able to see any comments or reviews you've left about those locations right there so you won't have to navigate to another place within the app. If you don't use Google Maps for this sort of thing, more specifically if you don't use Maps to store lists of places you have been to or want to go to, then you may not find this feature useful. If however, you do keep lists of places and you have lots of locations or even just a few stored, seeing any reviews you left about each place could help you remember what you thought of that location the first time around. If you're looking at your lists then you'll see these reviews below the initial listing name for each location.
As mentioned above the beta version of Maps now also supports leaving comments on your list locations. These are comments that you leave personally and can basically act as a caption. So if you particularly like a specific dish at a restaurant you like to frequent then you can leave a comment on that location in your list that will state that detail just below the name and above the review you may have left for it.
The latest version of Google Maps Beta is version 9.69, so if you're below this version simply update and you'll have access to these new features, and since this is a Beta version of Google Maps these will be rolling out to the stable app sometime in the near future most likely, but there is no indication of when that might be so users who don't want to wait for that may want to consider installing the beta. In addition to these changes, any contributions you make for locations in Maps that become popular will be highlighted and Google will alert you to this status. Essentially the app will send you a notification whenever a contribution becomes popular, though you can toggle this off if you don't want these notifications in the first place. As for features that aren't live yet but may be added down the line, Maps seems to be getting the ability for users to share a locked current location in addition to the real-time location sharing option, which should add some more user choice for those who don't want to share their real-time data. Maps may also soon begin promoting the use of Taxi services from time to time. All of these changes both live and upcoming follow the most recent change to the stable version of Google Maps which was the addition of the notifications for step-by-step transit directions that were added just a few days ago.