The official announcement comes on the heels of Zachary Levi revealing to USA Weekend that he had been cast as Fandral, but was forced to drop out due to an extended Chuck workload. While I feel for Levi, I'm actually very pleased that Townsend has stepped in, as I find him to be a bit more Errol Flynnish than Levi. (Though pulling up his Google Images reveals a guy who looks a lot more dashing than Chuck Bartowski. Wow. I might have to eat my words on that.) I'm anxious to see the once-and-never Aragorn get another shot at the fantasy genre, and prove himself to be dashing.
I'm not familiar with Asano's work beyond Mongol, but he turned in a very charismatic performance, and I'm always thrilled to see casting directors look to countries other than Northern Europe. But my heart really couldn't beat any faster than it is at Stevenson's casting. He'll be perfect, and it's awesome to see him get another shot at the Marvel Universe since it doesn't look like we'll ever see him return as Frank Castle. Filming begins in January 2010, and from there it'll just be one big geeky countdown.