A Legionnaires' life is a difficult one, for the only starting contract you can sign is a five-year contract with a 60-day probation period where you can leave at any time. Most can't take the life and desert, for it is not a life of guns and glory, you'll spend more time behind a mop then behind a rifle.
And in response to the common misperception that the Legion will accept all sorts of criminals and miscreants, that is not true at all. At least, not anymore. A full background check is made on you, including a full check by Interpol so if your some deranged axe murderer they'll find you, then they'll turn you over to the police.
If you do join up, you'll either serve in mainland France or if you become a paratrooper in Corsica. Serving in the Legion means serving overseas, and you'll see Africa from the eyes of Djibouti and Algeria. If France is involved in a foreign war its the Legion that gets sent first.
The French Foreign Legion does not cater to criminals, so if your a psychotic axe-murderer you won't be let in, instead you'll be detained and sent to the police. They do perform a full background check on you, one that runs through Interpol and the largest police agency from your home country. So if your from America like me, the FBI will be contacted.
And as you bash France for its lack of military victories, the French Foreign Legion operates outside the French military, and has performed excellently when Legion affairs are left in Legion control.
From the instant you join from, providing you don't desert, the instant you leave, the Legion will always have your back. A man I knew inside was caught with cancer during his service, they paid for all his medical bills, paid for his family to fly across the continent to see him, paid for all of them to fly home, and paid for the funeral and had several officers there in attendance.
And a few things of advice for potential Legionnaires, when you go to the recruiting station, don't bring anything you can't live without, do bring a few locks to guard your stuff, and make sure you can march 10 miles and run 2 miles at the drop of a hat.
Best of luck if you do join.