Iron Dome deals with artillery rockets such as Russian Grad, Uragan, Smerch, Iranian Fajr-3 and Fajr-5. Saudi Arabia does NOT have systems which can deal with this type of rockets.You have to look at it form a techy POV - Iron dome does not bring anything "new" to the table.
There is a multi layer system, which will be further supplemented by THAAD.
The current system has proven very successful in shooting down iranian BM's via Yemen.
Patriot and THAAD are against ballistic missiles.