Even though I thought the story was sort of average, I felt it had enough of those moments to put the episode somewhere between good and great, although I would have hoped for more from a story with 2 Masters, 2 Doctors, 3 different generations of Cybermen, and most of those characters being killed in some form.
Overall it has been a bit of a disappointing run for Capaldi's final season. Don't get me wrong, it's been consistent throughout, and even though it's had no major low's imo, it hasn't the big highs either. It hasn't been a bad season, but Capaldi's first two seasons were so damn good that this was a bit of a letdown by comparison.
Hopefully the Christmas episode is a stronger swan song for Capaldi/Moffat.