It is quite easy to learn the basics of the ability system, but as you acquire more and more abilities the opportunity arises to really add some finesse to your chosen setup. The real fun starts when you begin exploring the Ability Wheel to find abilities which fit well together, and design the kind of build that you really want to play.
Let us say you like doing lots of damage from a distance, and you choose Pistols and Assault Rifles as your main weapons. As you play, you discover that quite often you face groups of enemies, and that you are vulnerable when they get close to you. You therefore decide to develop abilities which ‘hinder’ and slow down your opponents, so you can more easily move around and shot them from a distance.
You also soon realize how much more effective you can be when you use abilities which synergize with each other. So for your ranged build you scour the Ability Wheel for all abilities who contain the key word ‘hinder’. Luckily you find them all over the place.