This is a fun economy card, because it offers substantial return for a low investment...but only in the right deck, and not always in the smoothest way.
If we assume that nothing has happened to increase/decrease the runner's hand size, then the best return you could get from Sweeps Week would be 5 credits. That's a net 4 credit gain; that's the same as a Hedge Fund for substantially less up-front cost. But it relies on the runner holding a full 5 cards, which is far from guaranteed. If the runner has 4 cards in their grip, then Sweeps becomes a marginally worse Beanstalk Royalties (but not a transaction: BABW is not interested).
Because the value of Sweeps can fluctuate over the course of the game, the best play is generally to hold off until you can get maximum value from it, and then drop as many as you can in a single turn to make it rain. While this can be very frustrating and slow, it does also act as a little bit of insurance against HQ runs by protecting your agendas from easy access. Of course, when the runner sees a Sweeps in your hand, they might decide not to draw up to 5, keeping your hand clogged for even longer...you may end up playing a Sweeps at a suboptimal time just to clear out your hand or get the credits you need to rez a crucial piece of ice. But you might also topdeck a Sweeps when the runner happens to be holding a full grip, which can be a lifesaver.
This card is worse in a deck that does brain damage, for obvious reasons. Oddly, though, it might be slightly stronger in a deck that tags or does net/meat damage; runners are more likely to keep their hand stuffed as insurance against Scorched Earth or Snare!, letting you turn it around faster.
One interesting synergy with Sweeps week is Mental Health Clinic. You get to make money from the clinic, and then more money from the Sweeps when they take advantage of the larger hand size. Nice!