Although some people simply want a rough stucco look on their ceiling, the primary reason so many ceilings are stuccoed is to hide a poor drywall job. Yes, stucco will cover many faults. It is also very forgiving to work with.
Whether you apply it with a compressor system or with special looped rollers it is fairly easy to get on evenly. If you want to put any kind of design into the stucco, just wipe swirls at it with a paint brush, bristle brush or sponge -- or even just dab into wet stucco to create those long hanging spikes if that is what you want.
If you blow it and want to start over, as long as it is still wet, simply scrape it off. Once it is dry, you can re-wet some stucco, even years later and scrape it off but the cement based stucco will not come off. In that case just scrape off the high points and put drywall right over it to start over.
How do you paint the edge between a smooth wall and a stuccoed ceiling? With great difficulty if the stucco flows right up to the wall. That is why most stucco applicators will put a piece of masking tape on the ceiling all around the room first, and pull it off while the stucco is still wet. That leaves a smooth band around the edge. Looks like trim? Actually it is just there to allow you to paint the wall a different colour and get a clean cut line between the ceiling and the wall.