I can see why some fans might have quite a bit of affection for this one.  It's certainly cool to see the short-lived Curator return from his brief cameo in Day of the Doctor.   I certainly enjoy the sense of him and UNIT running around using the Under Gallery against the Eleven.  However, there was something somewhat mid about this story that I found held it back for me.  It isn't even bad, it just didn't quite land anywhere that left me excited.  I guess for all the fanfare and big names, I couldn't quite connect with the story, plot, or characters in a way that left me feeling enthusiastic about the audio.  It's a satisfying enough adventure and conclusion to this set with the Eleven, but I can't point to any moments that really stuck with me other than the whole idea of the Under Gallery itself, having fun features like a bottomless pit and really feeling like the sort of home a being like the Curator would have.  There's stuff to like here, but I really wish I felt there was a little more heart to The Curator's Gambit.