I would say that the Progressive movement was quite successful in bringing issues related to worker's rights to the forefront of American consciousness. At a time when the revolution of Industry had begun to taken a firm hold in America, when the titans of industry or robber barons had begun to assert their grasp of American social and political orders, workers' rights seemed to be a very distant concept. The acquisition of material wealth had done that to quite a view ideas. The Progressivists were fairly powerful in bringing working conditions and compensation as issues that needed to be addressed. The Muckrackers did their part to expose working conditions as being unsafe or unsanitary and demanding change. The call for unionizing workers in receiving a more equitable status in compensation and benefits were calls initiated in the time period and still heard aloud today.
In my opinion, the progressives' record on working conditions was really quite mixed. This is in part because they did not really try to do much at the national level. Even such things as the Triangle Shirtwaist Company Fire did not lead to national laws. Some states did pass laws, others did not.
You can see that they were not really all that successful at regulating working conditions just by looking at what FDR did in the 1930s. At that point, he was still trying to get federal laws made on this issue (and many were struck down by the Supreme Court). This shows that the Progressives had not been all that successful.
The question isn't quite clear, so I'm assuming you mean evaluate the success of the movement in terms of working conditions.
Because so much of the country's population at that time was living in poverty, and working long difficult hours to get to even that level, the progressive movement had to get most of its membership from the small middle class (about 5% of the population at the time). The lower classes did not have the education, time or opportunity to participate in reform efforts in a meaningful way besides labor strikes, which were virtually all unsuccessful.
Later, after Teddy Roosevelt became President, some real reforms were introduced for the first time, but more because of the President's popularity and initiative than by the efforts of progressives themselves.