Get a long, hard look at the new characters, skills, features, and more.

Borderlands 2 builds upon the gameplay elements introduced in its predecessor. It is a first-person shooter that includes character-building elements found in role-playing games, leading Gearbox to call the game a "role-playing shooter". At the start of the game, players select one of four new characters, each with a unique special skill and with proficiencies with certain weapons.From then on, players take on quests assigned through non-player characters or from bounty boards, each typically rewarding the player with experience points, money, and sometimes a reward item. Players earn experience by killing foes and completing in-game challenges (such as getting a certain number of kills using a specific type of weapon). As they gain levels from experience growth, players can then allocate skill points into a skill tree that features three distinct specializations of the base character.

Returning gameplay features from the first game will include the unique, cartoon-esque cel-shading graphic style, 3-branch skill trees, class-mods, and four-player online cooperative modes. New features include a more expansive and customizable weapons system, reworked four-seat drift-able vehicles and vehicle physics elements, and dynamic quest systems. For example, taking too much time to save a friend in a quest may result in their death and the failure of the quest, which will affect the story as the player progresses. Technically, the game world will be all connected, rather than loadable levels for each region, allowing accurate viewing of the entire world from a given point rather than the first game's premade "Skybox".

In addition, the AI system has been reworked for the game. Non-enemies will populate the game world more often and will travel around different locations depending on the time. Enemy AI will encourage teamwork, such as flanking, as well as taking cover when wounded, though lower level enemies like Psychos will still embrace the mentality of, "Wow that's a gun! I want my face in front of it," according to Gearbox VP Steve Gibson. Shooting enemies will stun or cripple them depending on where they are shot. For a change, enemies will be intelligent enough to climb and traverse difficult terrain to pursue the player. Enemies will also be able to interact with each other. For example, certain enemies can heal their teammates, boost their shields for defense, or use them as shields to protect themselves.

Source - http://en.wikipedia.org/wiki/Borderlands_2