I think the biggest problem with IDT is that they are very serious about setting goals for the year, but they handle them terribly. The goals are generally enough to keep you busy full time, or close to it. However, they add stuff every week that is also a full-time commitment. And, at the end of the year you are held accountable for the goals you didn't make. Also, goals are based on what the company wants, and not necessarily a reasonable assessment of what the company is capable of. For many strategic projects, there is literally no understanding of what it takes to accomplish that sort of task. Basically, just management doesn't know how to grow the company, and they are not willing to acknowledge what they don't know. This can make daily work at IDT incredibly stressful. Furthermore, an employee can contribute amazing things every day and never hear a good job, but one tiny mistake that doesn't even affect customers results in a formal reprimand. This is not consistent across all departments, but many people have experienced the stress of a company that can't plan to achieve its goals, but also wants extreme accountability.
Similarly, the whole raise system is different across departments. Departments that are valued can provide raises above cost of living, and other departments get minimal raises. The company is more interested in justifying why you didn't get a 3% raise than they are interested in figuring out if you might have actually deserved more. Also, the budget for raises means that some departments have to take money away from other good employees if they do want to give one or two people a better (still uninspiring) raise.
The Iowa location is the main location. It is geographically isolated. I think that drives the whole raise system. There is only the University of Iowa as competition for scientific talent. IDT just expects you to accept the system, and they are willing to let good employees just leave. I was really happy with my contributions to IDT, and I thought they were too, but when I asked for some recognition it was pretty clear that they didn't think they had to do anything to keep me there. So, I left. I firmly believe that if you ask for a raise or promotion from managers you have worked hard for, and they don't respond with an enthusiastic "I'll see what I can do", then you have to leave. Also, really dumb lectures and no recognition for major achievements. That's a real thing at IDT. Management is based on time served, not skill.
I can't recommend IDT as an employer, but it's not an evil corporation. It's hobbled by bad management, and meager opportunities.