There are some things that really bother me about Ugolino's situation. He's in the 9th Circle of Hell, specifically Antenora, because he betrayed his country. Straight-forward and understandable. However, something that I think Dante frequently disregards is that most things having to do with humanity aren't always straight-forward. For example, say Ugolino betrayed his country because he was desperate for money to feed his family. Maybe that's not a great example, but you get my point. Dante never looks at the reasons people commit the sins that they do. Look at Francesca and Paulo. As Amy mentioned during her presentation, Francesca was forced into her marriage with her husband, which probably affected her decision to cheat on him with Paulo. Like I said, the reasons people do what they do are almost never simple.
Another major thing that bothers me about Ugolino's situation is the extent to which he suffers. I understand Dante is all about proving 'Divine Justice.' However, I personally thing that Ugolino paid for his sin of betraying his country before he even entered Hell. I mean the man was locked in a tower and starved. He also had to watch his SONS and GRANDCHILDREN starve and DIE because of his own sin. And as if that isn't enough, his survival instincts took him over, causing him to eat their dead bodies. And as if THAT isn't enough, now he's forced to spend eternity in the depths of Hell.
I'm not saying that what Ugolino did wasn't worthy of punishment. We don't really know how Ugolino's actions affected his country and to what extent. However, based on what Dante wrote, I'm a bit skeptical as to whether what Ugolino did actually warranted what he got. If he betrayed his country because he was simply a greedy traitor, then I see why he ended up in Hell. However, we don't know enough about Ugolino or the situation to determine why he did what he did, which I think is quite an important factor in determining a man's fate.
Call it pity, but on some level I think watching your sons and grandsons die because of your sin is enough "justice."