So after spending a bit playing around, here are my first thoughts.
Game play is completely different than previous Tomb Raider games. Do like the new combat system.
Graphics are just amazing!
Open sandbox is like playing Far Cry 3 all over again, along with the base camps and "skills/perks" using the same system. (Gain experience, gain rewards).
And I can see why they rated it PEGI 18+. They haven't held back on the gore and gritty aspects of the surroundings. Already seen poor Lara get crushed several times and impaled.
Only issue I'v found so far (and reported elsewhere) is with the Nvidia cards and FPS loss. My GTX 670 keeps going from about 40 FPS to 10 at random points, random artifacting and crashing. Only fix I'v found for the last two is to run the GPU fan at full speed to keep the temps down.