The Sword of Kahless was very average for me. It starts off with a lot of talk that makes it sound like we're in for a treat, particularly as I enjoyed Blood Oath so much. Kor being back was a hoot, and I enjoyed having him back in season seven all over again.
The episode soon decends into dullness though. Kor and Worf squibbling is silly, and I thought that having Toral being the enemy was a bit random. I agree that it was a nice callback, as back in TNG he was just there as a plot point. It didn't help that I hadn't seen all of TNG when I first saw this episode though, so I didn't know who he was or what role he'd played before until well after.
In the end though, knowing who he is doesn't make the episode any more exciting!