Well, the most of the characters state it's on a case by case basis. Some Circles are very lenient of their mages (such as Monthsimmard), going so far as to allowing some mages freedoms such as not having to live within the tower. Others, namely Kirkwall, were borderline gulag-like facilities where mages were punished with tranquility and execution for even the slightest mistakes (not crimes, mistakes: so much as even voicing opposition to Meredith's reign was grounds for Tranquility).
I view Fereldan's circle as something running in the middle of the pack: They aren't outright hostile to their mages, but Greagoir is a fairly stern, austere Knight-Commander. That said, Greagoir, while wary of mages and not quick to trust them, is reasonable and rational. He'll listen to reason and will not let his feelings or piety interfere with his duty and judgement. He even has a vitriolic sort of friendship with most of the senior mages. He's not going to do any mages any favors, and he'll follow his duty to the letter, but he won't persecute them or target them or treat them with overt hostility and animosity like Meredith. As well, he was willing to let certain mages perform business or duties outside the Circle if they were trustworthy enough. And his reign was certainly a relatively benevolent one, as none of the mages really had any problems that didn't come from themselves (like Anders and Jowan, who were more or less responsible for their own problems).