Corruption. The Awami League was the party that led Bangladesh to Independence. Recently, they tried to offer some number of government jobs to veterans of the independence struggle. This was seen as nepotism (since most such veterans would be members of the Awami League, or their friends / relatives). The initial student protests were then taken over by, depending on who you ask, religious fundamentalists, Pakistan or the CIA. The current govt is seen as a US puppet, while the BNP are seen as pro-Pakistan.