By using ABS, the amount and style of brake can be adjusted so as to suit the possibly slippy track...If you need every details of how ABS works, you may refer to your operational manual
Actually, not many people use ABS nowaday for most of the touring car equipped with front solid axle. I myself will apply ABS when playing F1 in a rainy day under a low grid track...
Basically, useful only if you know how. Simply put technically it does work . . .. imaging you have an electronic finger that can pulse say 10 times per sec., and if your equipment (esc or GP brake servo) is responsive enough, then brake will be applied 10 times per sec (otherwise if equipment is not responsive, the effect will not be noticeable). As such esc/servo may get hotter and burnt out if overloaded. As to how useful it is ??? it will depend on your driving style, car setup and track condition etc etc. as other C-Hing have pointed out.
Hope this helps.
PS: some of you may have fast pulsating fingers perhaps . . .. ha ha