If it's legal, I have no problem with it. People elected them to use any legal means to futher their cause, and if that means being obstructionist, they're just doing their job.
In Australia, minor parties and independents have held the balance of power in the senate for a couple of decades (about to end though
) and whilst some people get peeved that 5 democrats can block 40 Liberals, I'm not. The minor parties are usually elected to hold the balance of power for a reason-it's the only power they can get, and it stops the government in the lower house from being unchecked, as will practically happen when the new senate is sworn in later this year.