The Divergent Facebook page has my thoughts here (along with pictures!), but I’ll put them here too:
Recently I saw Theo James’ screen test with Shailene Woodley, and I was sure within seconds: this was ‘Four,’ no question. Theo is able to capture ‘Four’s’ authority and strength, as well as his depth and sensitivity. He is a perfect match for Shailene’s incredibly strong presence as Tris. I’m thrilled!