I think he's a great choice. It's the first time EON has gone for a director who isn't a "workhorse director" (i.e. someone who can point the camera and make things pretty, but isn't really a director's director). Forster is a young, energetic rising talent who loves to try new things.
When we look at his resume of the past few years, we get an idea of what Forster's capable of. MONSTER'S BALL and FINDING NEVERLAND display his aptitude for bringing out dramatic performances (even from Halle Berry - quite the accomplishment). STAY demonstrates his very detailed and complex visual imagination (don't get me wrong, all of his films are very visual, but STAY is especially visual in its storyline - the visuals create an entire secondary narrative), and STRANGER THAN FICTION shows his ability to handle character-based comedy with a lot of skill and artistic integrity.
So what has been consistent about Forster? Well, his films are well cast. They have had very big talent attached... Halle Berry, Billy Bob Thornton, Heath Ledger, Mos Def, Johnny Depp, Kate Winslet, Dustin Hoffman, Ewan MacGregor, Ryan Gosling, Naomi Watts, Bob Hoskins, Maggie Gyllenhaal, and Emma Thompson are some of the names he's worked with since 2000. And Forster doesn't simply cast well... he gets them to deliver with great performances.
The other consistent thing about him is his attention to visual storytelling. His direction is always very thoughtful and intelligent. That's a very new element for Bond, really, since the general mode of filming for any Bond film has been "point the camera, make sure the shot looks pretty, and roll!"