Assuming you dont have an IR or IMC its only value is enabling you to transit a class A CTR such as Heathrow and fly at night (assuming you have a night rating).
In both instances flight is not permitted under VFR, so for example a low level transit of Heathrow can only be given under a SVFR clearance.
If you have an IR or IMC it enables you to continue to fly in visibility which would not meet the criteria for VFR but avoids you having to declare IFR.
(I assume you know the minimium met conditions for SVFR so no point in trotting those out).