Honestly, it’s just… well, see for yourself. I guess it comes down to what you want out of a stageplay; if you wanted something in the vein of My Immortal, then you’re in luck, and I’ve gotta tell you that I’m not in general opposition to the idea. Once I got over the fact that it was, y’know, JK Rowling authoring it.
It occurs to me that there are people alive today too young to remember My Immortal, and that when they encounter it for the first time, assume it to be intentionally satirical in nature, especially given how many bad fanfic tropes it brings together all at once. Well, lemme tell you something about that: it created a lot of those bad fanfic tropes. I had friends in the fanfiction.net trenches back in 2006, and they assure me that that’s how a lot of people wrote back then.