IIRC, in SR4 you could spend Edge to be first in an initiative pass or spend Edge to gain another action in a combat turn. With Seize the Initiative it appears not only do you get to go first in the initiative pass but also gain as many actions as the top initiative roller and go first in all those passes as well. Is this correct? If it is correct it seems to unfairly handicap anyone with any sort of initiative enhancement (especially those who spend a large amount of essence, power points, etc. etc. to gain that advantage). Spending a single Edge point negates the benefit of spending 5 essence or 3.5 PP unless the high init character spend Edge as well.

It doesn't add to your initiative score, it just moves you to the top of the order - so that on any pass where you HAVE an action, you get to go first.