score:8
Witt Hotels has some excellent information on Istanbul, which I have personally used and recommend reading. I have not used the Istanbul tourist pass or Museum pass myself as I did not deem it worthwhile for myself and based on the 'attractions' I wanted to see.
To clarify, there are two passes, an Istanbul Museum Card and an Istanbul Tourist Pass
The tourist passes have options to add public transport.
Adult $75.00 USD, Child (Age 2-12) $35.00 USD
Adult $200.00 USD, Child (Age 2-12) $140.00 USD
Updated with recommendation:
Get the 3 day Museum Pass for 85TL and Istanbul Kart to get around. Its cheaper and the additional "attractions" on the tourist pass are quite tourist oriented and may be marked up a bit. You can definitely get cheaper local alternatives for the cruise/ferry etc.