Let's get the bias-clearing part out of the way right up front: I love Tintin. I've read pretty much every Tintin story ever published, I own most of them, and when I was very small my dad and I used to read them. He'd be Captain Haddock, I'd be Tintin and we'd narrate our way through each adventure, sitting side by side in my big yellow chair.
(It took forever for me to figure out why Andy Serkis's Captain Haddock sounded weird in the trailer; it's because he doesn't do my dad's distinctive pronunciation of things like "Blistering barnacles!")
As a lifelong reader, I think I have a decent say in the debate over whether the Tintin comics are racist in their portrayals of people who aren't white Europeans. My answer? Yes. Duh. Absolutely. Of course. Let the apologists argue over whether it was on purpose or whether Georges Remi was an innocent product of his times; I prefer to cede the debate entirely by admitting what is plainly obvious: Tintin, as a comic, is racist through and through. One has only to look at the Congolese of Tintin in the Congo to see this. For further examples, I recommend the black crew members of Cigars of the Pharaoh, the Muslims of The Red Sea Sharks, the hired guns of Rastapopulous and his gang in Flight 714 and dozens more.
Tintin himself is vehemently anti-racist, and is often seen sticking up for downtrodden locals over the objections of imperial powers (see: Zorrino in Prisoners of the Sun, Chang in The Blue Lotus). The trouble is that said locals are always portrayed as incapable of protecting or defending themselves, and in need of Tintin's intervention for their own safety. You could make similar cases about the inefficencies of provincial governments around the world that Tintin travels to, the political instabilities in various regions (the Balkans, the Middle East, South America) that Tintin regularly soothes, and so forth, but that's not the point.
The point is, if you get caught up in the comic's racist tendencies, you're going to miss just how freaking good it can be. Tintin is an adventure hero, and he's a bit of a Mary Sue for pre-teen boys; without much of a personality of his own, he travels around the world, fights crime and solves mysteries. Who wouldn't want to put themselves in his shoes? The comic is drawn well, the stories are decently complex and frequently comment on issues of the day, and there's plenty of comedy (from Captain Haddock and Thomson and Thompson, among many other sources). It's all right to label Tintin as racist; that's what it deserves. But if you pigeonhole it away with Rudyard Kipling and Doctor Doolittle and all the other racist literature that also happens to be very good, you're missing out on some eminently readable and visually stunning childrens' tales.