Pros
I used to work on the boring parts of the internet, and am now excited every day to come in and work on getting people great dates. It's a small company that iterates rapidly. The C-suite sits among everybody else and is very accessible. We're expanding very rapidly right now, so there's definitely opportunity to grow. On the perks side (aside from insurance/401k and such), we have great office food and outings. People in the office tend to arrive after 10am and leave at before 7. But nobody looks at you funny if you have to leave earlier, and some people keep earlier hours (9-5/5:30).
Cons
The cons are related to the tradeoffs of a company with ~50 people. Communication can be ad-hoc as opposed to process-based. This means you should talk to your colleagues to find out what's going on instead of expecting everything to end up in an email .