Who reads this Durood Shareef in excess (day/night) will gain the maqaam or position similar to Wali, Qutub, Abdaal and Ghouse. The gains include that all the sins however big or small will be forgiven even if they are equal to the surf of oceans. (Note: I heard from my pir o murshid that ibadah that includes forgiveness of all the sins, only refers to minor sins and not major sins.)
And ont he day of judgement, the reciter of this Durood Shareef will be given his/her Aamaal Naama (Book of Deeds) in his/her right hand by the angels and by the Barakah of this Durood Shareef the balance of good deeds will weigh more and he/she will receive the special Shifaat of Nabi Kareem Sallal Laahu Ta'ala Alayhi Wa Aalihi WaSallam and he/she will be given Jannah without any Hisaab o Kitaab.