The game is available now in some stores. People are already playing it (at least the PS4 version).
Only very positive previews, game looks obviously great, and most of the time it's apparently 60fps with some occasionnal dips when heavy action scenes.
"it was incredibly fluid and looked to stay at 60FPS for majority of the time"
http://press-start.com.au/2014/01/24/preview-tomb-raider-definitive-edition-60fps-60fps/
EDIT: Nsanity, those numbers you have are just a guess from a Neogaf member. Nobody knows yet if X1 version dips under 30fps. X1 could be 15-45 FPS for all you know with 30FPS average. And 60fps average (meaning mostly sustained 60FPS) for PS4 is real apparently.







