Improved Initiative is pretty useless simply because a d20 Initiative roll is far too wide a range. There needs to be way more modifiers on the initiative roll, and realistically, Initiative should be either a smaller range (d10) or a curved range (2d10).

The fact that a 20 Dex Monk w/ Improved Initiative can even lose initiative to a Full-Plate and Tower-Shield wearing Fighter with a 10 Dex and OverSized 1H Weapon makes me sick, let alone the chance being about 1 in 4.