Pros
I've been honored to work with effective and knowledgeable fellow transit experts who are dedicated to their craft and are willing to help at a moment's notice. Using technology to make sure we specialists and managers are very helpful; I managed to go very far (as disorganized as I am) due to the help of the senior management. They are willing to aid with professional development (where your knowledge base may expand). Also - they will give you autonomy to perform at your own rate; as long as you make proactive moves to change the landscape. They believe in ethics and in lending a helping hand to others. Check the handbook - they are flexible with leave and the like. Good to have. A phone and health/insurance subsidy is also good since you'll be at the job site and would need to rely on said phone
Cons
It comes down to the cooperation of your clients. Some clients are going to be easy to work with and will give you the tools to succeed. Others may not be so easy to work with, and getting those things you want (say, an actual budget) could be like pulling teeth. Your effectiveness is as good as the clients you have, and thankfully it's nothing to do with the company. - Just a little light on the benefits (transit and 401K), but it's negligible if you negotiate effectively.