I played a game of Warmaster Ancients, once. There were some mechanics that left me feeling uncomfortable; it seemed that the closer one got to the enemy, the more manouevrable one’s units were. However I was up against a very game-y player, and he may have been bending the rules. I have heard it suggested that Hail Caesar does some of the same things that Warmaster does, but rather better.
Hail Caesar is, as someone else posted, a good game if one’s mates are affable and chilled and rather less good if they are competitive or had a hard day at work. Also, because commands often fail to activate, it’s best if each player has a couple of commands and some decent generals. Playing Black Powder, I once had a friend who failed all his rolls and couldn’t move for around 90 minutes of game play, and who consequently lost the will to live.