Abilities provide team play

It feels like there's a lot of thought that went into character's abilities and how they play. Symettra's turrets can be used to notify you of enemies coming in a specific path, you don't need to use them strictly for defense. Some shields allow for your team to shoot through them, but others can't. This encourages people to stick with the person with the shield and to help each other out in more meaningful ways than throwing med kits, ammo boxes, etc. which is typical of first person shooters.

It adds a lot of depth to the game, as you can work with people. It's a lot of fun, specially with friends, as you can try new strategies and new compositions with different abilities.