Grouping Node Comment in Views
I know an old post anyway. There two solutions to this, here is one, but for this you need to define the type of the view as comment view right from the start, However another solution is that (Assuming Review 1, Review 2 are nodes being pulled and a relationship is set on the comment and node), right below the Title block you have the FORMAT configuration block, set it to Unformatted list and to display the fields (Notice: I have not tested on other formats such as table etc), click on Settings after the |pipe symbol and you can see Grouping field Nr.1  with a drop down, choose nid as your grouping method. In other cases there might be Grouping field Nr.2/3.. and so on. This should be able to group all your comments together for a node.