Pros
It's a growing company with the associated growing pains. That's the challenge I like. We are blazing a new trail and adding to our technology and service tool kit constantly. Lot's of learning, lot's of training, and the opportunity to make a difference in outcomes. Won't find this with large companies where ingenuity is mired in politics, fear, flexibility or indifference. Been there, done that. Sales is closely aligned with service delivery (IT). Excellent communication.
Cons
It's hard. That's why it's fun. Example: personally I've sold a "first" new service offering several times at Stage2Data. In these circumstances I can't just hand the contract off to the support team (and we have a great support team). To ensure customer satisfaction I am involved every step of the way. That's the Con because it takes away sales time. The next contract is that much easier to execute. You need to have an entrenched entrepreneurial spirit and be able to handle the responsibities.