Pros
ST has a vast portfolio of products, so you get exposure to end to end product development including the softwares. Managers promote you to do research on newer topics and appreciate the same. Wide variety of tools available. ST has its own fab which enables interaction directly with the people who actually develop the process. Avg experience of employees is more than 10 years, so freshers have good mentorship.
Cons
In general, there is a very negative image about the company among the employees. Environment is not good. Employee-employee interaction is not healthy. Politics also happens a lot within teams. Seniors tend to dominate the junior employees. Growing in the company is pretty difficult as there is lot of competition. Most of the senior employees have been in this company right after college and hence don't have much exposure to other companies and to the culture in the industry in general.