First of all, Luxoft is an outsourcing company. You can be out of luck if you get into bad project (there is a bunch of them). Many people were dissatisfied and leaved the company. However, I was lucky and pretty happy with my project, the team was good and a customer was adequate (this is not always the case). However, it was a long-lasting maintenance project and most of the tasks were boring. I can remember only one big feature implemented from scratch. If you are a creative person loving innovations such a project is not for you. Another thing: if a new project is initiated, Luxoft hires dozens of people at once. If a customer decides to cancel it later on (there were precedents), you are in trouble. You can move between projects, however, and Luxoft tries to keep people rather than push them out (there is such a thing as "bench" where you can spend up to 2 months being fully paid and Luxoft looks for a new project for you during this time. When this time expires, you get fired). From my experience, most of people managed to find another project.
Luxoft can promote and does it often, but only if a person is nothing or is doing nothing. If you are good in writing code, you will never be promoted - if you start managing, who is going to make your complex job? That's why "monkey-testers", for instance, get promoted very often (their skills are very, very low as the name implies).
Recap: Luxoft can be good or bad, it heavily depends on the concrete project. I believe it applies to many other companies as well. Don't expect to be promoted if you are a coder.
