Read the wikipedia link for a run-down on als.
For the majority of applications it's pretty much useless. In terms of performance, there are 1001 better things that you can spend your money on.
However, for fappity fap fap wankie wank value there's no denying it's good.
So spending bulk dorrahs aiming to achieve an end result of "getting antilag" is probably a bad idea.
Most people who are using als simply enabled it because it was a feature of their
ecu, and somewhere along the track figured why not fap over some sweet bangs?