Pros
No actual vacation policy - take as much or little as you need, decent yearly raises based on performance, ability to be a one-stop-shop for your clients and vendors. Technicians and admins get dropped into networks with little to no documentation and expected to learn/document/and fix all at once - which is enjoyable.
Cons
You will get treated like a piece a meat. There will be late nights and early mornings. There will be times when several of "your" clients are all having a bad day at the same time and you have to prioritize. Dealing with the fallout is seldom enjoyable. On call 24x7 - even during time off. Too much time off can result in no raise for the year - based off of a company average. Management is more or less hands off - which makes getting a feel for your performance a bit difficult throughout the year. All business hours need to be accounted for in billable 15 minute intervals.