In AX 2012 user interface has been changed significantly. AX looks now much more modern and I would say, Office 2010-like.
However there were not so many new controls added (I will write about each of them separately). The variety of different visual experiences can be achieved now with the new extremely cool property of form controls – Style.
This property defines general look & feel of the control, which can be then customized with other properties.
For example, Tab control has the following styles:
And regular AX 2009-like tabs, by the way, – Tabs.
Action pane can be with Standard or Strip style.
Form design has a lot of styles, like ListPage, DetailsFormMaster, Dialog, SimpleList, Lookup and others.
Many other controls have style property as well. This property really helps to change the visual appearance of control in the very easy way.