PvE: On General Vezax trash i decided to try out this seal. IT WORKED WONDERS. The mobs were constantly being stunned, making the tanks and healers life sooo much easier, i couldnt believe i had never thought of it before.
PvP: Many have said that SoTM is the best seal for pvp aswell as pve. I tested out seal of justice for a while in random battlegrounds (i know its not arena) and found that it procs very often, but due to diminsihing returns on the stun i get a lot of immune messages. This would provide a maximum of 4 seconds fo stun, after which you can hammer of justice for a total 10 seconds of stun.