Pros
High performers are rewarded *well*. I've personally never seen a commission percentage as rich as it is at Proofpoint, and they pay accelerators for over-achievment. There are many opportunities to advance in a growth company like Proofpoint. SaaS and Security are both hot, and Proofpoint does both well. The executives address the whole company on a regular basis, and they all seem very intelligent while being down-to-earth and focused on customers.
Cons
Because the sales department at Proofpoint is fast-paced, the environment favors the ambitious self-starter. The training is good, but the security landscape is complex, competitive, and it keeps changing. If you're going to join the sales team, strap in, as many of my peers here are helpful and yet intensely competitive (myself included). The team I'm on operates with a startup-like intensity. If you don't like that kind of thing, this may not be the place for you.