This story is difficult to appraise at times. It's host to some genuinely compelling character drama focused on 11, Amy, and Rory; it has a really fun mystery going on; the slow invasion and the domestic scenes it allows are both enjoyable. It just really sucks that the episode crashes and burns at the final hurdle. This is generally attributed to behind-the-scenes drama. Could it have been worked around regardless? Maybe... but it'd be a rare director and producer who could actually pull that off, if so.

All things considered, it's worth noting that The Power of Three is still watchable despite this problem, and for all that it has a frustrating ending, I'd say it's still decent on the whole. It has its fair share of memorable moments and also does a pretty good job of setting up the Ponds' imminent departure.