Pros
No one comes in to "work" - they come in to express their passion. Work rarely feels like work. Talented people that can deliver are given a huge amount of freedom and opportunity. Yet it's okay to be "new" - the company is quick to recognize raw talent and provide mentorship to help shape successful careers. They'll give you a chance when no one else will if you have the drive. Experimentation and risk taking is encouraged (within reason), and I'm constantly surprised by the level of innovation that can be found at such a small agency. Much of what they do us cutting edge - for example, they were early adopters of Node and React.
Cons
It's a small company (for now) and isn't as stable as working for a big corporation. Passion is expected - if you lack passion, you probably won't have a great experience. If you start working at Brain Bytes, consider it a "ground floor" opportunity.