This cleanup enables the game to run a bit smoother, without having to handle the extra, unneeded objects. AwesomeMod also does a 'cleanup' in the game, such as removing extraneous vehicles and objects that have been created by bugs or left by Sims that have died or left.
It does add some special traits and interactions, as well as some overall 'fixes' for the game (such as clothing or hair category fixes). AwesomeMod handles story progression much the same way as the Twallen/NRaas mod.