Bluehole and PUBG Corp have rolled out a major update for PlayerUnknown's Battlegrounds, bringing limb penetration system that was announced a while ago, along with optimization and some additional improvements to the original map, Erangel.
Bullet penetration system is now in place, but it only works on arms and hands as legs are unaffected. It should still put an end to the notorious hand shields in PUBG though, as arms and hands will no longer block any damage to the body parts behind them.
Players who get shot in the arms or hands, will take full damage to whatever body part is behind them. For example, if a hand is blocking the head, the player will take full headshot damage. For an unspecified reason, legs are not affected by this change. Shotguns will not penetrate any limbs, but then again, the shells are always less affected by the shield hands due to their inherent spread.
Both Miramar and Erangel got improved due to addition of dynamic weather, but Erangel also got some additional changes. Small clusters of houses have been added to some areas of Erangel, presumably with loot inside, while some areas near the river are no longer just barren, open beaches but rather rocky areas with cover.
PUBG should have better frame rates now as another bit of optimisation got added, regarding weapons that are not currently equipped. Additionally, smoke and flame from vehicles have been optimised for better frame rates and level streaming has been improved for the same pourpose.
Quality of life improvements don't stop at optimisation however, as stack splitting has been improved as well. Players can now adjust quantity of bullets or other stackable items they want to drop with a slider and can use Alt+Left Click to drop half a stack or Alt+Right Click to drop the entire stack.
Overall, players have been waiting for this update for a long time and received it well when it actually landed. You can read full patch notes on the official Steam Community post.