Advantages:
Each rider pedals/coast as desired. Especially great for newer tandem duos.
A great conversations starter!
Confuses the heck out of folks behind you who want to count your cadence!


Disadvantages:
By not being constant in or out-of-phase, it can create tandem sway, especially when stomping/climbing. If leaning hard into a corner 'could' cause a pedal to scrape, but most tandems (unless really racing) do not lean into corners that hard.
If you want to pedal in phase, or out-of-phase, with an ICS tandem, stoker has to visually check captain's foot position and then co-ordinate her pedal stroke (or disable the ICS system).
More expensive and complex than standard pedaling system.
Has 3 bottom brackets instead of 2.
A bit heavier (if weight is a concern).

Test ride both systems and then decide TWOgether!

Yes, have ridden ICS equipped tandem. No, do not own one.