It could stand to look more fiery rather than like pure polygonal cylinders.
http://i.imgur.com/QSP4e.jpg
http://i.imgur.com/vlChS.jpg
Just as making something reflective and wavy doesn't make it look like water, and making something red and translucent doesn't make it look like fire. Yet unlike water, it shouldn't be much more of an extra FX strain to make it more convincing.
Can't just link to any jet engine nor their state. There's a distinct difference in shape and size, also how powerful the afterburner is. At maximum capacity, it's a very clean cone with those signature rings like in the screenshot I posted. Weather and temperatures also has an effect. However I do agree it's not perfect and again, DCS World has no flyable jet fighters so I doubt afterburner / jet flame cone is a priority right now - When FC3 is released as a module, it'll probably get some love.