While I don't want to get into it much here since there is a GoT thread in this subforum, it wasn't just Jon who was let down as the series progressed. Pretty much all the characters became caricatures of themselves because they didn't have any writers who had a really nuanced sense of the characters.
Jon always did better when he was taking action, he was kind of bad with words and indecisive, but once he was in a situation where he HAD to respond, he was enough like Ned that he would just step up and do it. One of those moments was going after Ramsey. Another one was in Hardhome, which ironically wasn't even in the books but is one of the best original passages in the series. Jon needs the wildings to speak for him and convince the other tribes that he's on the level and won't betray them -- but when the hordes of the dead spill down on the community, he goes beyond words and shows his honor through action. He orders all the Crows back into the settlement to buy time for the fleeing wildings and regain the dragonglass (a task he fails in), but it's a freaking crazy moment where so many people are dying left and right and Jon never flinches, and he doesn't care how many of the crows follow him. He just runs back in, not knowing what he would face, and ends up facing down one of the wraiths, and is one of the last people to flee the settlement, in the process saving a decent amount of wildings (although many are still lost).
It is one of Jon's best moments, revealing his courage, his faithfulness, and his fighting ability.