GD '42 is part of the Tactical Combat Series originated by The Gamers. It includes the long-awaited 4th edition of the rules. The BGG entry summarizes changes in the 4th ed. as follows:
Vehicle impulses increase operational tempo for tanks
Introduction of spotting ranges
Streamlined assault rules
Combined Area and Point Fire table
Introduction of morale for vehicles
Enhance combined arms effects
Artillery subsystem improved.
I've been a fan of TCS since the beginning, finding that it seems to be less 'gamey' and more authentic than many tactical systems. The game rewards using historical tactics. The one important weakness of all previous versions was in the armor rules, which didn't capture the dueling nature of tank vs. tank battles. Often TCS battles didn't feature much armor, or the armor was mostly on one side or the other, but when both sides had tanks the games were a little off.
These rules have been in gestation for years so they should work well. I'm hoping that their appearance will finally bust open a log jam on TCS games. I've particularly wanted to see a TCS treatment of Arracourt.
GD '42 continues a sub-series within the series, games telling the story of the elite German army formation GrossDeutchland, which started the war as a regiment and ended it as a panzercorps. Previous games in the series so far are GD '40 and GD '41.