Vantaggi
ALTEN has been around for about 20 years so they have impressive exposure to most sectors. I'm in the telecoms division and there are quite a lot of opportunities, and they keep getting interesting projects. The projects themselves are also of great quality so it's technically rewarding to work on such projects when you are working on-site for the client. The managers also keep track of your evolution and are there when you need them on anything. The annual career-management is also well lead and the process is in place to ensure that things go well over a period of 5 years.
Svantaggi
The flip-side of being at ALTEN is that because of their size, financial compensation is quite poor. I have seen some extremely competent (and experienced) engineers paid quite poorly compared to what they should be getting. There is also little to no reward if you do extra hours at a client's site or if you deliver more than the client expected, which is morally damaging.