We take current and former employees as research objects, and analyze the textual and numerical data according to 41,000 anonymous reviews of employees from Amazon, Apple, Microsoft, and Google employees, which is collected from a workplace community, the Glassdoor website, that provides company reviews. We discuss the differences between former and current employees' needs for each of the four companies based on reviews on the Overall Rating of the employees and the five dimensions (Work/Life Balance, Culture & Values, Senior Management, Career Opportunities and Salary & Benefits). The results reveal that the current employees prioritize Work/Life Balance and Senior Management, while former employees value the company's Senior Management the most. Next, we explore the textual data of former and current employees' comments on the company: a text mining analysis of the high-frequency vocabulary of positive and negative evaluations and employees' suggestions for the company, and it is found that current employees have positive comments on the Work/Life Balance of the company, former employees have positive evaluations of the company's Senior Management and Culture & Values and both current and former employees are not satisfied with the company's Senior Management.