Thank you for the feedback. The cart content is editable from the confirm_cart.php page created by the checkout wizard. It is added to display tax and and shipping information that could vary based on the shipping address entered in the checkout process. Unlike the previous version that had a 3 step checkout process, the new checkout process reloads the cart contents and updates shipping and tax using AJAX so that the checkout process is streamlined into a single page.
The update cart button is removed because it is replaced by "update" links below the update fields in the shopping cart process. This concept is popular for smaller screen designs so that people can update the quantity and then click update right below it. It is similar to what you will find on the amazon.com shopping cart.
The primary features of eCart 6 are responsive cart design, AJAX cart updates, more checkout form designs that include client and server validation, streamlined single-page checkout workflow, and new payment gateway options including Paypal Advanced, and Paypal In-Context.
Let us know what features you would like to see in future versions using our feature suggestions area in the community section of our site. The features we added were based on user feedback about what people wanted to see, so your feedback can be very valuable in helping us determine what might be included in the next version. We always appreciate customers willing to give their opinions about how we can improve our products.