The bill was originally proposed  to give blanket amnesty to those who committed political offenses since 2006, specifically ordinary individuals (and not leaders) who joined rallies and political protests.
But an amended version has expanded  the scope of the measure. Critics warned that politicians, military generals, and police officials accused of corruption and human rights abuses will be given amnesty as well. In particular, the opposition said the bill will ‘whitewash’  the crimes of former Prime Minister Thaksin Shinawatra who fled the country after being found guilty of plunder by a local court.
Thaksin was deposed by a coup in 2006. His younger sister, Yingluck Shinawatra, is Thailand’s prime minister today. According to Thaksin’s critics, the bill will allow the former leader to return to the country and recover his wealth which was sequestered by the government.
Interestingly, the Amnesty Bill is also being rejected by the allies of the government, namely the Red Shirts. The group feels ‘betrayed’ since the bill will also grant amnesty to former Prime Minister Abhisit Vejjajiva (now leader of the Democrat opposition party) who is accused of ordering the bloody crackdown  of anti-government protests in 2010. Almost a hundred Red Shirt members died during the violent dispersal in 2010.
In other words, the bill is being criticized by both the opposition groups and government supporters.
Bangkok Pundit described several provisions in the measure as too broad :
…it is so broad and could include so many different times of crimes. It is impossible to have perfect clarity, but specifically including certain crimes which are applicable and specifically excluding certain crimes would make it much clearer who is included and who is not.
The bill will have dire political consequences , said Anuthee Dejthevaporn:
If the ‘Amnesty for All’ bill is passed, then consider the consequences that may come. What will our children say, if one day they also get killed in a future political conflict and they have to fight for the justice all over again by themselves? What will our children say, when they realize that we, their parents, could have done some big things to create the true justice in this land for them, but sadly we didn’t?
The Nation, Thailand’s leading daily, explained why the bill is divisive 
Thailand has enough real problems without the added burden of a political move that will only worsen the national divide.
Why is it that a “reconciliation” plan advocated by the ruling party is threatening to tear the country apart? The answer is simple: The government's legislative moves do not seek to rectify the root cause of Thailand's strife, but are amplifying it instead.
Twitter users reacted by highlighting the controversial features of the bill
Amnesty Bill leads to reconciliation? Far from it – even Govt supporters have different opinions on blanket amnesty.
— veena T. (@veen_NT) October 27, 2013 
House has passed 2nd reading of altered amnesty bill, which could bring Thaksin home and allow him to get money back.
— tulsathit (@tulsathit) October 31, 2013 
— Sunai (@sunaibkk) November 1, 2013 
— teamkorn (@teamkorn) November 1, 2013 
After a 19-hour debate, parliament approved the bill on November 1. As expected the opposition walked-out of the session. The senate  will tackle the measure next week.
A protest  was immediately organized which was attended by an estimated 10,000  people. Curiously, the Bangkok local government vowed to assist protesters by providing mobile toilets  and extra lighting in the event.