Just returned from our trip, and my DDs (7 & 6) loved getting their passports stamped. They enjoyed talking to the CMs from different countries, and there was rarely a line at any of the Kidcot stations. When we returned to the condo at night, DDs would put the appropriate stickers from each country in their stamped passport. They have a really nice souvenir from WS that didn't cost a fortune (plus the great Epcot WS button).
The Kidcot stations are sponsored by Sharpie, so there are lots of colored Sharpie markers at each one. The CM will sign the passport in regular ink, and the kids use the Sharpies to color Duffy. You can pick up a Duffy at any of the stations (i.e. each country does NOT have a different Duffy). My kids spent about 30 minutes or so coloring Duffy at our first station, then they got the handle stamped at each country. To spread it our a bit more, you might want to have them color just some of Duffy at each station. I think my kids would have grown bored coloring 11 Duffys, one at each country.
Our first and favorite Kidcot station was in France. It sits inside the main gift shop right and there's a cafe seating area right behind it. DH and I enjoyed a croissant and adult beverage from Boulangerie Pattiserie while the kids colored away.
I also noticed that there was some sort of free Cars passport (paper) at a few of the stations and it was a Cars Challenge. Maybe someone else knows more about the Cars Challenge? But the $10 passport is much nicer and worth the money, IMHO.