It's a great game. We don't usually use it for post-apocalyptic games but just for generic sci-fi (we disregard jamming power armour, etc., for that - though it's a great wee rule in its own right).
The Simian X supplement is worth getting in PDF as it has quite a few more "generic sci-fi" additions.
We find that it works best when warband numbers are kept fairly low - certainly well below 10.
It's also good with wandering monsters/aliens. What we do is stat up our six grisliest aliens or rogue robots and then roll a d6 at the end of the turn. A 6 means that a monster enters from a random table-edge or other spawn point. The monsters always activate on three dice after the players' turn (each monster counts as a separate player if there's more than one) and attack the nearest models. But you could give each a 'mission' to follow if and when it enters the table ("retrieve artifact X"; "harvest the organs of humans only"; "prevent lifeforms from escaping", etc.).