I have just downloaded BCIV this weekend and must say "good show". I was a fan of the BC1st edition and it replaced Arty Conliffe's Spearhead as our Brigade/Div scale Miniatures game. It is very quick play for a low terrain/ high model count scenario. Works best in the desert and russian plains in my opinion. Derived from the fantasy warmaster series it generalizes the stats for each stand (platoon) to realy 5 numbers. The units are rated by a general Anti Inf/ Anti armor AP/AT score. Hits are then allocated to the stand, after any saves are made. Command is handled by a "push your luck" system that handles the nationality differences to our satisfaction.
Also a plus is the authors after finding some flaws in the 3rd edition-- apologized (gasp!) and made the fourth edition available quickly and without a GW Upcharge to all previous owners. A+ product and thank you MArk Fry and Pendraken.