I was at Berlin for 2 weeks. Even tho i didn't like the city as much as other european cities, i still had my fun :)
I will start with the staff. Most of the staff are very nice and won't bother you if you don't break the rules(drinking/smoking). The people that take you on the activities are very nice, but some of them don't really explain everything too well.
Next, activities. I must say there were some fun ones and some let's say a bit boring. Going to the beach and the zoo was really nice but some of the walking tours are quite boring.
The accomodation. I was in the campus and i must say the rooms are really nice, they look just like in the pictures. There is always warm water, but for the problem was the ventialtion, the windows are just not enough to ventilate a 5 person dorm, or toilet.
Food/cantine. The food there wasn't my favourite, maybe the worst part about campus. I mean yeah they try to feed 100 people, but come on at least keep us fed or something. Here is a picture of an ice cream you can get at hockey pockey best ice cream place in berlin
The most important thing, classes. I must say i kinda feel scammed. The teachers are that good and the material is kinda not on level with the level you are on. I was placed in c1 even tho i'm somewhere around high b1, low b2, BUT, the classes weren't even on level a2 by me.
Sleeping on campus before 2am is kinda dificult. Even tho the rules are that you need to be quite afte 10pm, a lot and i mean a lot of people party and just scream on campus.
Room service isn't that good. I got my towels replaces only once and i think for summer time, when it's hot out and you sweat and shower more, they should have at least changed them twice. One of the towels was a bit ripped but nvm ig.
I found it cool that you don't need to attend activities and can do whatever you want with your time. Something cool i recommend checking out is the Monsterkabinet.
Something i think isn't very fun is the key replacement system. You need to pay 80€ for a lost key. That is a loooot of money for a key
To summarise. Berlin is not that fun if you are not 18. You can't go clubbing. Other things such as public transport, are kinda nasty. The tram smells like piss and on the metro there are a lot of people doing drugs. But i think you should still visit Berlin