To explain your project well — whether to colleagues or newcomers — you need to break the builder’s familiar train of thought.
The familiar train of thought is to focus on upcoming features, unsolved problems, outrageous corner cases, or recent incidents. In any interesting project, there’s never a shortage of these.
The unfamiliar train of thought is to focus on what you’ve already solved — and solved elegantly. Naturally, you’ll want to talk about the feature you’re currently wrestling with — the one with a long, dramatic backstory of being rewritten four times in three years. But it’s far better to highlight something useful to the user, especially if it’s straightforward. That’s what your audience will remember.