I know a lot of expats living in Berlin who are all impressed by the public transport. Granted, they are mostly not from Europe and I personally also prefer to take the bike whenever I can, but it's far from "notoriously bad".
Op is right, though. The PT in Berlin is certainly quite large and offers quite some options on paper. But it is notoriously crowded, unreliable, and sometimes just plain slow.
Kind of right, but it's not THAT bad. I commute from Neukölln to Prenzlauer Berg every day and taking the S41/S42 trains is by far the fastest way of getting to work. Car is slower and it's quite annoying to go through the city, bike is a bit slower but I prefer to get my exercise by running.
Another story are the renovations and building projects that just cut whatever part of the public transportation down for days/weeks. There are alternative routes one can always take, but I prefer to stay out of the hot U-bahn during the summer days. There can be some nice surprises, like that one Monday morning when this guy decides to start smoking heroin in a full and sweaty U8.
Edit: Forgot to add that the trams are awesome. Air-conditioned, fast and comfortable in the eastern part of the city.
In what way do you feel it's unsafe? There are a few notorious party lines (U8, M10) which can get pretty crowded with tourists on weekends but this is just annoying at worst. There is also a large amount of people begging on PT in Berlin but I never felt threatened by them. I don't take PT much here regardles, usually just ride my bike.
Don't know how unsafe it is, but it is a bit nasty to see the stuff that goes on in U-bahn stations such as Moritzplatz, Kottbusser Tor, Schönleinstraße, Hermannplatz, Leopoldplatz, Boddingstraße et.al.
Never felt unsafe, but the heroin usage and dealing is very open and in your face during the commuting hours.
Slow, yes. That's a main gripe i also have mostly because the routes are bad. But crowded? Have you been in the Paris or London metros at peak times? If anything it's worse if we are talking only about crowdedness. Even in places like Tokyo, known for their perfect schedules and reliable PT, the amount of people stuffed into a single train is on another level.
UBahn is (surprisingly frequently) used by people that appear to have some kind of mental disorder, yelling at and attacking other passengers, to a lesser extend by what I would describe as wannabe gangs, people under the influence and plain drug criminals.
Nevermind that the subway has a lot of strict rules in that regard but Berlin being Berlin they are hardly ever enforced.
Just an anecdote: I once witnessed a really large muscular and completely drunk guy attacking an actor that was dressed up as Friedrich II., including what looked like a rapier or small sabre. The situation was definitely unsafe for the actor and (if he would not have managed to protect his rapier, because that was what that drunk guy was after) potentially dangerous for anyone else.
Another day I had to interrupt some aggressive youngsters trying to rob other passengers in the middle of the day. When they left it turned out they were armed with knives. Not a fun thing to learn. I notified the subway driver once I got out (the gang was moving from wagon to wagon), but he essentially did nothing to stop them.
I have not witnessed such stuff in other cities' public transport. And certainly not in that frequency.
