As far as I am aware the station itself is still New Street just the shopping centre/concourse is now Grand Central, where as it used to The Pallasades.
I do think they are supposed to be doing something more at platform level, to let more light down there. Not sure how but apparently " the station will be enclosed by a giant atrium, allowing natural light throughout the station and to all 12 refurbished platforms." I do not think that bit is quite finished?
And there is/will be 36 new escalators and 15 new lifts - reaching every platform.
If nothing else how they have done the refurb, keeping the station open and operating is nothing short of brilliant tbh. The station has been rebuilt while continuing to serve 170,000 passengers who use the station each day.