Answer:
I think that general effect is negative, GST (or VAT) is the worst tax that authorities created.
1-st, it increase general cost of life in the country, because applied to most goods and services, so all people just pay more for everything, real income of households is lower thanks for that tax.
2-nd, while it supposed to redistribute wealth, in fact GST most heavily affects middle-class, that spends most of their income to taxable items and (as proportion from earning) poor citizens, who spent even bigger chank of their income. So GST role in social justice is not so positive as it could look.
3-rd it is bad for business, because reduces demand, require efforts to administer and often own money to pay. Yes, in theory the consumer pay, but in fact in many cases businesses have to pay GST before they get money from the buyer.