To answer your question, it is buisness professional Monday-Thursday, and business casual on Fridays. For the most part, the outside sales team typically wears suits or at the very least, slacks, tie, and a sport coat.
As far as culture, I don't really know. From what my friend tells me, it's a pretty laid back environment with a bunch of Type "A" personalities. I know my buddy hangs out with some of his co-workers in the evening. I'm pretty sure it's a lot like any other sales job from that aspect.
As for the above comment, I'd leave your decision making up to your personal experience. Most of the people who come to this board have either had a bad experience, are competitors, or are employees of the specific company. No matter who you are searching for concerning a staffing company, you will always find negativity.
If you think about it, Ajilon is one of the top three companies in the world regarding accounting and finance. They literally put hundreds of people to work each day all over the country. If that is the case, then I think the amount of people who are unhappy and posting on this board is pretty small in comparison.
Remember: No one ever remembers what you do right, but they never forget what you do wrong.
And for the record, I am not an employee, competitor, or a disgruteled person with a chip on my sholder. I'm in the staffing industry and happened to stumble across this board.