I've always wanted an FPS where melee combat was fully integrated into gameplay, not just a single OHK knife button.
Basic overview:
1. You spot an enemy running under your ledge.
2. You press the correct button and jump on them, knocking them over.
3. The enemy is knocked to prone and prone speed, while you are slowed to crouch speed. This only lasts a second or so.
4a. You shoot or melee the injured enemy while they are down, killing them.
4b. The enemy's teammates kill you before you can finish off your target.
Think of this as sort of like playing as the Hunter in L4D. If you pull it off right, you kill them. If you get it wrong, the enemies will kill you before you do lasting damage.
Brink has knockdowns and finishing moves. You can knockdown a player with your weapon, which opens up different choices - The downed player can decide to get up or shoot while he down. If the downed player is melee'd while down, it results in a OHK and he dies.
Also, when you incapacitate a player and they are waiting for a Medic, you can get up close to them finish them off with a melee attack. This is more efficent than shooting them, since it takes quite a few shots to kill them.
I appreciate the decisions SD made, suche as
1) the knife is a choice, not a standard weapon for all.
2) If you choose to have a knife, it takes up your secondary weapon slot.
3) Situations where a melee attack will kill you outright, are heavily limited.
I will never understand why players want melee in FPS games. the "S" tands for "shooter," not "stabber," "slicer," "smasher" or any other melee-esqe word. If you want to stab people and/or perform OHK's, go play an RPG and roll a Rogue.