This was sweet, but I'm not sure how much it added to the overall story of the Captive Prince trilogy. I can't really justify giving it any higher praise than "nice". It's not simply because of the length, as I've read other short stories and found them more satisfying - including the other Captive Prince short story (Green but for a season). 
 Yes, it's always going to be enjoyable to see more of Damen and Laurent together, after the final events of King's Rising, and the steamy scenes were as well done as you'd expect. The story did manage to develop their relationship a little further and perhaps laid to rest a few more of the ghosts from both of their backstories. It also gave a small insight into how the princes are working on combining their two countries, with the beginning of a mixture of cultures very nicely done. But personally, I was happy with the ending of the trilogy, and I didn't think there was much more closure required or any questions particularly unanswered. 
 The blurb calls this an epilogue to the main trilogy and if it had come in that format - in the book itself after the story closed, I would have been delighted with it. However, as a standalone, I'm not one hundred percent convinced it was worth the PS1.99 purchase price. I've seen it described as fan service, and in my view that's probably a fair description. I didn't time myself reading it, but it was less than half an hour. Honestly I expected more.