Your enjoyment of this OVA will largely depend on what you would be expecting coming into the OVA. If you wanted more of Kaori like me, sadly you aren't going to get it. If that wasn't the case, I thought it would be clearing up backstories in the series but it didn't seem to do that as well. Just showing a short part of what the life for the the rivals of Kousei competing against him was, for me, not good enough for the plot of the OVA which had gained quite popularity before being released. Coming into theOVA, the plot and the story just isn't what the viewers will expect watching the OVA.
However, as in all of the episodes of Your Lie In April, the OST and the music delivered as it always has and made the viewing experience really satisfying.
Overall, I wouldn't say it was an anime that you shouldn't watch because it's that bad, but I wouldn't say it delivered to the expectations of the viewers.