Well, yes, he was... though he is not how I picture Tyrion, he has the acting chops to pull it off. Tyrion is a very complex character. I think he's my favorite character in A Song of Ice and Fire. I get the shudders at the very thought of bad casting for this series that I love. But so far, so good. I usually think of Dinklage as a very serious kind of guy, but he can be funny, too - and it's Tyrion's wry sense of humor that makes me love him so much.
Check out the news story at The Hollywood Reporter.