First of all, you can't rate this short OVA/Episode, so I gave them a normal score.
In this episode, there is one character added. Although his name was not told, it's still a character.
There's no different with the sound and the animation so let it not surprise you.
What makes this episode impressive, is a sight in the future of Angel Beats!
After the episode ended, it stated ''next stage''.
We ''Angel Beats!'' lovers, hope for a new season or a clue what happens next.
I highly recommend this episode AFTER you finished the main Angel Beats! series.