Avantages
My first professional job was with GLMV, and I really appreciated all the training and experience I got there. My boss was an excellent architect and manager and allowed flexibility for employees personal situations. The work was steady, and the type of projects we took on were relatively recession-resistant. They froze salaries rather than firing people when the recession hit, and did not to hire and fire employees with each major project.
Inconvénients
The social environment was very conservative, and some employees, (though not the management) were overly expressive of their religious viewpoints. I don't know if there was a religious policy in hiring, but (despite being diverse in other respects) every employee but one in the Houston branch was a Christian, and it did impact the office culture. The Houston branch of the company is relatively small, so probably didn't offer much opportunity for advancement. The work we did was not particularly exciting or groundbreaking from an architectural design standpoint.