Love and Monsters is actually a pretty good episode that doesn't deserve the hate it gets, IMO. Fear Her definitely has room for improvement, and I do consider it one of the two truly lackluster episodes with little to redeem themselves from RTD's era. The Zygon Invasion/Inversion and Dark Water are pretty dire, the Zygon story for being so heavy-handed and preachy, Dark Water for the incessant Moffat Monologues. But I'll gladly watch any of them over Forest any day.It's not "worst, Period". Its the worst in your opinion, which is fine. I'd say that Love & Monsters and Fear Her are a lot worse. I also hated The Zygon Invasion/Inversion and Dark Water a lot more. As a bad episode, I consider In The Forest of the Night to be a middle of the road "bad" episode. Heck, there are episodes people love (like Human Nature/Family of Blood) that I consider worse then Forest. Its not even remotely good, but its not even the worst of the Capaldi era in my opinion, much less the worst of NuWho or Doctor Who in general. In my opinion, at least.
And I am of the opinion Human Nature/Family of Blood truly is one of the great masterpieces of all Doctor Who.