Vantaggi
Very friendly and easy-going atmosphere. Being still a "small sized" company little time is wasted in useless meetings or unfruitful bureaucracy. It is a great place if you want to learn a lot, while working on projects which are the right size to be interesting, while being manageable by few people.
Given a project, I have always been given quite a lot of freedom on how to proceed, with a constant feedback on my results an the possibility of quickly receiving advice or suggestions.
The working culture is also wonderful: the time schedule is really flexible, and people have always been understanding and helpful if I needed extra time for some important reason (such as the Austrian bureaucracy). There is also free coffe and breakfast, which is always a nice plus :)
Svantaggi
It is a small company, so the career opportunities are currently limited (but the company is growing, so I don't really worry about that). Being few people, you can't unload boring tasks to other "lower grade" workers, but it really is not that bad (in ML there can be a lot of "handwork", which is not always exciting).