-Not a "hot" technology employer. LM does not have the pull or allure of a Google/Amazon.
-A lot of the systems you will work on are very old/outdated, and the skills you develop here will only be helpful in the defense industry. Especially for software programmers, a lot of the languages used are fairly old, and from what I have seen from friends looking to transition over into the commercial tech sector, the skills you develop here are not attractive to other employers.
-Bureaucratic and slow paced; decisions need buy-in from multiple different managers (even if they are only tangentially related to the project), which requires many meetings and follow on meetings.
-Overall compensation package is not good. Salaries are below market average. No year end bonuses. Employees' performance is graded on a normal curve, and the nominal wage increase barely beats inflation. Health insurance plan is a common complaint among employees.
-Job security: current cuts in the defense budget and projected slowdown in defense expenditures point to a lot of belt tightening. LM has gone through a series of layoffs over the last few years. This has led to poor morale and has further exacerbated the next point:
-Political, territorial, and top heavy management. Some projects have more managers than actual engineers/workers. Some managers have no understanding of the technical product they are overseeing, which can lead to bad decisions and stressful/unreasonable demands on engineers.
-Lack of diversity.