Pros
The company is a group of individuals that really want projects to succeed. The culture is great, casual but professional, everybody can manage their own time as long as the work is done right.
Personally, I was given great autonomy and freedom to share my ideas and most of the time if not always they were taken into consideration, I think nowadays that is very rare and Impossible is really good at embracing new perspectives and listening to what you have to say.
You will be surrounded by kind, smart people that will help you and teach you whatever you need to do your job.
You can bring your dog to work and that can be really nice when you are having a bad day!
The office managers are great and always ready to make you feel at home, there is always plenty of food, coffee, and fresh fruit.
Cons
Sometimes people can take the casual factor a little too far but there is nothing that a good set of headphones will not solve!