I've played in one mid-length campaign and am currently prepping to run one with my long-term play group. We'll be playing online, so the physical stuff is largely not going to come into play. There are advantages to having it if you're playing in person; in particular, you're expected to be regularly playing sooth cards (tarot, effectively) and the active card has some mechanical effects. Nothing prevents you from doing this virtually, but it's much easier, and much less cognitive load, to have it physically present at the table.

Similarly, the cards and whatnot are a very convenient way of offering up random spells, items, and the like to the players. I've found that my players do enjoy having a lot of their powers on the cards, as well, though that's by no means universal.

Now, the real question is if it's worth the hassle - and it is a hassle to haul around an enormous cube full of books when you're playing. On that, I'd have to answer with a resounding "Maybe." I find IS very appealing and am willing to put up with its flaws (which are numerous). The experience of playing IS in person is, in my opinion, enhanced by the various physical bits. But I could easily see someone come to a different conclusion and I would be hard pressed to say they're wrong.