Common Sense's review rightly says that the consequences of your actions are not always readily apparent, and that's true for the person who isnt paying attention. The companion characters who accompany you, such as lilliana and morrigan, each have distinct moral and ethical leanings which should be easily understood after just a few minutes with each.
For instance, Morrigan is the daughter of Dragonage's version of the boogey man, and her demeanor suggests she's likely to do whatever will help her out the most, and she despises weakness. When you choose to help the poor or to allow an enemy to live without any request for gain, your approval rating with Morrigan will go down. When you kill her mother in order to obtain a spellbook that morrigan wants and ostensibly save her life, or make a particularly self-motivated decision, your approval rating goes up.
Lililana is cut of entirely different cloth. She is an immigrant with mixed heritage who grew to love the Maker while spending time as an affirmed sister of the Chantry, the DragonAge version of organized religion. Whenever you are met with a life or death decision, for all but the most vile of villans she will counsel for mercy, saying that the maker and the chantry will accept and reform anyone, no matter their sins. If you do not choose mercy, she will disapprove.
There are several other characters the player will meet and travel with throughout the game, each offering a different viewpoint and different advice to the player for each decision. Understanding each player's moral compass is key to realizing how your decision may turn out later on.
Spoiler alert: making this point requires a major decision spoiler.
Some decisions don't have a morally or ethically "right" decision. When you choose to start out as a dwarven noble, you are the second of three children of the dwarven king. your introductory mission takes you into the deep roads to reclaim a lost relic of your ancestors, but on your journey back to your home you encounter your elder brother, chosen successor of your father, lying dead on the naked stone. your younger brother shows up with your father and retainers and accuses you of the murder. after you are cast out of your homeland and join the Grey Wardens, you return to compel the king of the dwarves to lend you an army against the darkspawn with treaties signed generations ago, only to find that your father is dead and his throne empty. Your little brother, the true murderer of your older brother, contests your father's right hand man for the crown. Knowing your brother's actions, you may still support him as king. If you do, your father's retainer is executed and you learn at the end of the game that your brother led the dwarven kingdom to new heights of prosperity and abolished the caste system(similar to indian castes, if you are familiar with that social structure). If you chose to support your father's retainer, then your brother refuses to accept him as king and attempts to kill you. you find out later that the caste system was kept in place and the dwarven kingdom's economy sank deeper than the stone in which it used to thrive.
Those two outcomes become readily apparent as the player completes the quests necessary to crown one or the other, forcing the player at the very end to weigh the options of supporting a good and honest man who will keep things as they are, or a kinslaying and backstabbing prince who promises change that will be good for the people. Ether way you get your army, as the treaty compels the dwarven king to lend aid.
That is not the kind of decision i expect anyone who has not started highschool to understand. However, it is not an uncommon position for an adult or older teen to be in, where neither of two paths offer a completely good or bad result. There are many places in the game where what is right and what is wrong are not the most obvious, and you must rely on your comrades and your own moral and ethical compasses to make your decision.