Yeah, Gimple has been on point with every single episode he's written. I expect tonight's episode to be Emmy material for Lenny James if done right. There's got to be some interesting stuff to bring him from the brink of raving lunacy to the badass bow staff wielding pacifist he is in the present.
Gimple does have a good track record on this show when it comes to writing episodes. The weakest of them I think is "What's happened and What's Going On" and "Hounded" and even them I don't consider to be bad episodes.
Save the Last One - Shane kills Otis episode.
Pretty Much Dead Already - Sophia comes out the barn episode
Hounded - Merle hunting down Michonne
Clear - Rick/Carl/Michonne travel to King County and meet Morgan
This Sorrowful Life - Merle's Death Episode
30 Days Without an Accident - S4 Premiere episode
The Grove - Carol and "look at the flowers" episode
No Sanctuary - S5 Premiere,Terminus escape
What Happened and What's Going On - Tyreese death Episode
Conquer - S5 Finale Episode
He also has written.
18 Miles Out [Rick and Shane take Randall, end up fighting]
A [S4 Finale. The Claimers get Rick'd.]
First Time Again [S6 Premiere]
Although those three episodes credited two writers for each, Gimple being one of them.