Eurogamer can tell you this: what's been shown of Underworld so far is impressive and intriguing. It looks beautiful, it looks fresh, but it still looks like a Tomb Raider game. Crystal Dynamics appears to be focusing on why fans love the series as much as how to push it forwards, and that can only be a good thing.
There's still much more to be revealed, and it will be intriguing to see the new mythological environments Lara will get to explore. But so far, Tomb Raider: Underworld is looking spectacular. Much like Lara's tits.