Traditional notation is written in four clefs, when one would be adequate. Traditional notation is biased toward C major and closely related tonalities because it makes them easier to read. But all tonalities should be equally convenient to read and write. Traditional notation often employs numerous accidental signs and awkward key signatures which could be completely dispensed with.
Traditional notation tends to space noteheads in a deceptive and confusing manner.
The challenge is to devise a notation system that does not have these deficiencies.