These are EXACTLY the changes PC players have been asking for since launch. I'm honestly surprised that Crytek was able to react so quickly to what players were asking for. Most of these tweaks are in some way suggested in the PC Community suggestions thread! Here's some anolysis of the changes.
WEAPONS:
In short, the three main full-auto weapons have been nerfed. Scar, Scarab, and Feline have all had their recoil increased, and these three will probably suffer the most from the headshot damage reduction. Great change IMHO and I hope we'll see a lot more weapon diversity now.
Recoil has been increased for most weapons, and this is going to make the guns feel MUCH more fun and challenging on PC.
Most of the guns that were OBVIOUSLY better than others have received slight nerfs, and those that appear to have been worse than average received slight buffs. For example, in terms of Side-arm balance, the obvious choice of AY69 received a slight nerf with the addition of recoil, whereas the meh hammer received a recoil reduction.
The slight OSG nerf will probably put it closer to on par with the Gauss Rifle.
The only change that seems iffy to me is the buff to the Frag Grenade. Maybe PC gamers are just better at deciding where to throw, but it seemed plenty good enough to me.
The buff to the MK60 (recoil reduction) is probably necessary due to the headshot damage reduction (which I will discuss below).
MODULES:
Most of the weakest ones have been slightly buffed.
Nano Recharge and Energy Transfer-- which were the only Armor perks worth using-- received slight nerfs which will put them more in line with the other perks.
Mobility enhance was nerfed, which is probably meant to nerf the stealth enhance/mobility enhance combo which allowed players to pretty much infinitely run around while stealthed.
NANOSUIT CHANGES:
-Reduced armour bonus" of Maximum Nano-suit. It was a fairly powerful kill-streak, and this seems more in line with putting it on par with the gunship. One of the strengths of Cry2 is that Killstreaks are fun without being ridiculous.
-Headshot damage modifier reduced
THIS CHANGE IS HUGE, AND AWESOME. Crytek has essentially listened to players and, depending on how significant this reduction is, vastly increased player health. A few lucky shots could make a player go splat prior to this change, and how damage will seem much more consistent across the board. Firefights will go closer to how you expect. This will particularly nerf the SCAR, which was particularly potent at getting headshots.
All-in-all, amazing job with the first balance patch, Crytek. Far better than your competitors; you listened to your fans and you looked at the data.
Possible criticisms are: single-shot Jackal balance was very fun before, and I'll be sad to see it go if this was a significant nerf. Frag grenade might be a bit stronger than it needs to be now. Also, perhaps in exchange for the JAW nerf, you could make it explode at closer ranges with an increase damage falloff the closer you are-- this is mostly to avoid the frustrated feeling of watching a rocket disappear because you were just slightly too close.
Stealth enhance remains the only perk that is the obvious choice for its category, but this will be significantly reduced via the Mobility Enhance change.
Also, point fire enhance buff + laser sight might make this game somewhat easier for new players to get into, which is good. Cry2 multiplayer is very challenging and this might ease some players in.