Arrived Hauptbahnhof last night via train from Budapest. No problem at all. Not even a passport check at Keleti.
Have seen many migrant/refugees inside the station, as well as a tent city in front of our hotel. No feeling of being unsafe whatsoever, no disorderly conduct, only what seems like patient waiting on their part, with high but relaxed police presence. Saw lots of women and children, a few very cute babies, as well as many young able-bodied single men.
My questions are why are they sleeping in the train station? Are there no shelters for them? Are they waiting to get on a train to Germany? Are they limited on the trains? Sorry for my stupid questions (Emily) but I don't know and I really want to know the situation.
By the way, don't try to do any transaction at the OBB ticket office at HBF. There was a throng of migrants/refugees there. I don't even see how you can get through.
On a better note, I would highly recommend Motel One Wein-Hauptbahnhof right across from the train station. Brand new hotel, only 4 months old, very modern, clean, lots of "teal" color, great beds, excellent design space usage in the small bathroom. Very nice bar/lounge and breakfast area - way more classy than the usual €70 price. Only 2 stops to the city center on the red line U1.