Pros
You get the opportunity to work at Google; learn, grow, and have Google on your resume. Vaco benefits are okay compare to other vendor companies, but there are a few vendor companies out there with better benefits than them. Plus, I had to constantly remind them to send me benefit info.
Cons
Just like many other vendor companies and recruiting agencies, they DO NOT care about you. They come off very nice when they are trying to get you into the role, but they aren't your friends. Do not confide secrets about your job, seeking a new position, and especially being converted to full time at the company you were placed with. They do not care about you. As long as you're working where they placed you they are constantly getting paid for the hours you put in. If you look for another job or get converted they lose that income. Lastly, getting converted to full time is like seeing a unicorn. There's no chance that will happen. Don't believe them when they tell you it will happen. They are all sales people. Born with experienced to lie, lie, and lie. Whatever it takes to make you stay. Just do good at the position you're at, so you have the experience on your resume. But always be looking for a job because they can let you go any time they want (it's in the contract). Then you're screwed out of a job. Even if they said they can help place you right away after, they are lying.