Does a quilted jacket actually keep you warm, or is it just a shape we all agreed to like? Honestly, it depends entirely on what's inside it. A proper fill, down or a good synthetic wadding, traps air and holds heat. A thin one with barely any padding is just a padded shell, and you'll feel the cold straight through it by the time you've walked to the bus stop.
Where it falls short is anywhere you need to look sharp rather than snug. It's not a jacket for a smart dinner or an office where everyone else is in wool coats, because quilting reads as casual no matter how good the colour is, and it sits bulky under a blazer in a way that never looks intentional. It's also not brilliant in proper rain unless the shell is treated, because wadding that gets wet stays wet, and a jacket that's gone heavy and damp against your shoulders is miserable for the rest of the day. As for what it fights against, skip anything already textured or fussy underneath, a chunky cable knit under a quilted jacket just makes you look like a duvet with arms, and avoid pairing it with another puffed or quilted piece, a bag or boots in the same finish, because then it stops looking like outerwear and starts looking like a theme. Keep what's underneath flatter, a fine knit, a shirt, something with a clean line, and let the jacket be the only thing doing volume. The difference between a jacket that earns its spot and one that ends up at the back is mostly in details you can check before you buy. Feel the fabric between your fingers, a nylon with a bit of weight and a slight sheen wears better than a flat matte one that pills within a season. Check the stitching lines are even and not puckered, because uneven quilting channels let the filling shift and bunch at the hem within a few wears. Zips should feel solid, with a decent pull you can grab in gloves, and the inner lining should be smooth rather than scratchy against a jumper. Press the sleeve between two fingers, if you can feel clumps rather than an even spread, that's filling that will go patchy fast.
Given a decent one, they age well rather than just wearing out. The shell softens and loses its slight stiffness, the colour mellows a shade, and the jacket starts to mould to how you actually stand and walk rather than sitting like it's still on a hanger. A good one at five years looks lived in, not tired. A poor one at five months already looks flat.