Avantages
It's easy to gain invaluable experience as it's a small company that is understaffed for the overall workload to keep it running. For that reason, they will happily give you extra responsibility and tangible work.
Inconvénients
Understaffed - people are overworked and unhappy. Leaving at 5 means that you have to do the "walk of shame", because everyone stays on until later in the evening. Things are always left until the last minute, which means that there is a daily mad rush to get tasks/projects completed for a deadline that should have been done weeks prior. Poor culture - The company has been sued successfully numerous times because the senior staff is often encouraged to mistreat and verbally harass their subordinates. Meetings often have an aggressive and confrontational tone. Lots of finger pointing, internal politics, and extreme lack of integrity. Long hours & minimal pay - Expect to be overworked, and be paid well below market rate for a similar position. You will often be expected to work weekends with no extra compensation. Poor Leadership - Finally, don't expect any sort of gratitude from the senior staff for working overtime/weekends in order to keep on top of things. They will find some small task that wasn't done and berate you for it. Senior management will not hesitate to publicly humiliate you in front of your peers in order to make a point, and will get away with it since there is no HR at the company. They have been working there for so long that they think it's their right to do so.