It was disappointing to me because it wasn't the first time I'd heard the solution. It was like I had a spoiler for the chapter, because I was reasonably confident as to what it was. And while I've seen research linked to on LW that says spoilers don't decrease enjoyment, I definitely find they do, at least for me.

It was redeeming, however, that more complications were added on top of the imperius!debt. If it had simply been Harry winning with it, I think would have found the chapter dull.