A couple of days ago I bought 5150 Battalion Commander. I still have to finish reading the campaign part of book, but I have already read and played some test battles with infantry, vehicles and mechs separately. By the way, I found this book very well-organized. Also, differently from other Two Hour Wargames titles, this one includes points values for the different units of the 5150 universe.
Tinkering with the 5150 Paper Warriors miniatures and Gimp, I built a full company of Hishen and Star Army infantry grouped in stands. As I am playing in a reduced scale, each stand is 1.5cm wide and 1cm deep.
I played two games pitting a platoon of Hishen against a platoon of Star Army, each of them with a heavy machine gun team. In the first game, the Hishen panicked after losing a squad (in a series of failed crisis tests.) The second game was a lot closer: the Star Army was left with the platoon leader team and one squad. Each game did not take longer than an hour, and that is while I was learning the rules.
I also played some quick battles between tanks and between mechs, and tried some encounters between tanks and infantry just to learn the rules for overrun and close assault. Vehicle traits are more abstract in 5150 Battalion Commander than in some other sci-fi rules. Still, I got the overall feeling that each type of force (infantry, vehicles and mechs) has their role and advantages on the battlefield. I guess that is good, in a sci-fi game of combined arms. The mechs seem at first glance a little too powerful but I will need to play some more games to be sure.
As I wrote at the start of the post, these are my first impressions after some "test battles." The streamlining of the rules, compared to Star Army, results in a very fluid game. I plan on making some paper stands to represent tanks and mechs so that I can play large battles with this system.