I'm a huge fan of the Tintin books, and went to see the film. As a bit of a purist I was worried that it would end up being too Americanised, or that the spirit of the books would be trampled under the CGI and action sequences. I was actually very pleasantly surprised.
While not entirely true to the comics - and I thought it was a little too action/slapstick in places - I think it was as good an adaptation as I could have reasonably hoped for. There are a lot of potentially ruining touches Speilberg could have added, but mercifully didn't. For example, I'm relieved that he didn't attempt to bring Tintin into the modern day (as the books are definitely a product of, and commentary on, 20th century culture). Nor did he try to fiddle with the formula by bringing in an unnecessary love interest or any token minority sidekicks. Although the film suffered in places from being a bit of a "best-of" compilation, there was plenty of material that Spielberg didn't shoehorn in - Cuthbert Calculus, for example, and the whole Cold War era story arcs. Plenty of material left for a sequel or two, in other words - which I'll be keeping an eye out for.
To be precise: arguably the best thing to happen to the Tintin franchise in over 30 years.