I thoroughly enjoyed the film and plan to see it again. I liked it even more than I hoped I would. For one thing, the way scenes were stretched out, letting the tension build and build... I didn't know movies knew how to do that anymore (the first scene was especially brilliant in this way).
For another, something about the violence didn't bother me. I find myself more disturbed by film violence nowadays, but this -- gory as it was -- was sufficiently cartoony to never let me forget I was watching a Hollywood film. Compare to violence in The Hurt Locker, for example -- there I winced. In IB I was cheering.
Third, Christoph Waltz is going to be a big star in this country now. I hope he wins an Oscar. The Nazis in general were really well done. The Frankfurt Allegemaine said the portrayal of Nazis was spot on: "...as the pompous trash they were." A German friend of mine loved it, but thinks the German-dubbed version in Germany won't translate as well. She saw it in Holland, where they just subtitle.
After Grindhouse, I wasn't sure what to expect from Tarantino. Would he continue down the road of parody to self-parody? Thankfully the answer seems to be no. This is a mature effort and a thrilling piece of filmmaking.