The main advantage I've had, on silver status is the reduction in the cost of an additional bag for domestic flights, within Egypt; you get 2 x 23kg bags, in most cases, for economy and 2 x 32kg for business on international flights, but this is reduced to 1 bag, at 23kg & 32kg respectively, for domestic, if you don't immediately transfer to between the two flights (a right pain, as I always spend a couple of days acclimatising in Cairo, before moving on up to Luxor and Upper Egypt).
If I remember rightly, the discount is something like 15% for silver card holders, on all pre-paid extra baggage fees, which can be a hefty saving on what you'd pay at check-in.
Another advantage with the program, is that any domestic flight will earn a minimum of 1000 miles, which really helps with gaining & maintaining status.
The only problems I've encountered have been with other *A carriers being slow to credit the miles to my MS+ account, if using it as my FFP when booking flights with them.