Word has it that Obama wanted Lew for his reputation as a 'tough negotiator.'
The progressive side dislikes him because he has a penchant for the status quo, and is no genuine reformer, which come to think of it is probably not a bad description of the President.
The conservative side dislikes him because he is a tough negotiator, and the fact that they wish to disrupt the processes of an opposition government at any opportunity no matter the cost and the benefit to anyone else. It is certainly based on no moral principles or standards.
