A good impact can be pictured and described as “landing your airplane safely.” If you’re too steep or too shallow coming into impact, your “airplane” will crash.
One of the most difficult things about golf is that each of your clubs requires a slightly different angle to create perfect contact, which is often the reason you can be driving the ball great, but hitting your irons poorly. Ideally, with a neutral swing, you can do both parts of the full-swing game very well.