Pros
Looks great on a resume. A wonderful start to any medical career, or as a temp job. You get to interact with the physicians on a one on one basis and you often form close bonds with them, as well as the nurses, PAs, techs, and just about everyone else who works there. A great way to finally figure out if a medical career is going to be for you or not.
Cons
1-2 year contract depending on full-time or part-time status with little to no room for advancement unless you get very lucky. Usually not a big deal as they don't actually make you sign anything, but it's still a lot of pressure. Little to no benefits and the pay is horrible for what you're doing. Moral dilemmas can often arise when you're asked to chart something by your physician (such as the ever popular "smoking cessation" discussion) when it never actually happened, just to increase billing. Watch your back.