This article by Amira Hass is a must read for anyone who still entertains the illusions that Hamas is a bunch of angels with invisible wings, who are above corruption and cynical manipulation of power. She does a good job of puncturing the myth of Hamas's networks of charities, showing how they aim to create clientele. Here's how she opens her article:
"A resident of a refugee camp in Nablus, a member of Fatah, used to worship at a mosque that is identified with Hamas. As an employee of the public sector, he is one of tens of thousands of wage-earners who are not getting a regular salary. Once every few days, he would find a generous food package on his doorstep, put there by anonymous benefactors. Recently he began to worship at a different mosque, one not identified with Hamas. Since then there haven't been any packages. It's a story that is in accord with various impressions to the effect that Hamas finds indirect ways to reward its supporters."
Hamas has also proved that it can assassinate and shoot at demonstrators like the best of them. I would say that Hamas is different from Fateh in that while Fateh will talk about the "homeland" and the "nation," Hamas uses the language and authority of religion, which makes for a great and a dangerous camouflage.