Pros
Having hopped around and seen how several SaaS startups function both in terms of culture and work, I can honestly say that ProsperWorks is the place to be. Everyone on the team is driven and things move here at lightning pace, with genuine care being put into a kickass CRM product. Complete transparency and ability to communicate with higher-ups freely despite growth, and the culture is great. People are fun, relaxed, and unlike many places, doing your job is more important than looking like you're doing your job. If you do what you're supposed to do, not only will you get rewarded, but you can also do whatever you want. Your input is truly valued no matter where you stand in the company.
Cons
Many processes are still developing, but development is directioned and intentional, with rapid adjustments made. Hours are fairly long, with most people going home around 7:00pm - however, that being said, dinner is catered every day at 6:00, which is amazing. No 401k matching (yet). Other than that, honestly, nothing. Get on board if you can.