This does:

Increases the vehicle variation among peds
Increases variation among peds in all areas of San Andreas
Increases color variations for most vehicles
Ballas and Families are seen more often in Los Santos
Cheaper weapons and minor edits to clothes stats
More cars and peds in some areas
Some weapons do more damage
Gangs sometimes appear outside their territories
Gangs cause more trouble with law enforcement

and other things notmentioned ;-3

This does make things a bit more challenging due to the amount of rival gang members roaming around.

As always, back up your old files before using modded files!