It seems like it's tradition now for games to release out the gate with a day one patch. But Far Cry Primal's doesn't seem to have to fix any glaring or widespread issues, and just brings about bug fixes to make the prehistoric experience that much more harsh.
It was decided that expert mode was just too easy for PC players so your health has been halved and your aim assist has been similarly reduced. And be on the lookout as the AI can also shoot at you 1/3 faster than on Hard difficulty. Expert Mode was made to almost literally put you in the shoes (or wrappings) of a prehistoric human, making it a much more tense experience.
Other fixes include improvements to stability, improved lighting and better looking and more useful aiming reticle and improved destruction graphics when giant mammoths run rampant through the environment. Just some general enhancements, which is far cry (pun intended) from the cleaning up some games have had to have in recent past. Overall performance seems to be quite good, and you can look for our performance analysis very soon.
If you haven't had a chance to play the game yet, then check out our review to see if the game is the right choice for you.