Pros
They don't disturb you if you're on a client getting money for them; I've enjoyed the "sparkling moments" - it's cool to meet other people in the company and see that you're actually not alone (though most of them are managers).
Cons
Don't count with training... Unless you really fight for it, also don't count with getting raised - unless again, you fight for it like a mad man, whatever salary they are negotiating with you, they're getting between 50 to 60% more from the client so don't be surprised if you don't get placed. In term of work/life balance... It's all up to the client! If you have a good relationship with the client, he's the one that will keep your paycheck! Ah, by the way... If they tell you that "if you get fired, we will keep you and look for another position" don't take that! They will send you away on you the moment they lose the contract with the client you're at. I've quit from Amaris on my own because I got fed up with the client and with the Amaris management and decided to move on to another chapter in my life. Once I quit the "real problems started"... Got called to a meeting with the manager to be insulted because I was leaving the company. In a nutshell Amaris is a body-shopper... And one of the most aggressive on the market!