Short summary: Neutral since the experience was worse than most parties I have been too, but not negative since the cost was ultra low and drinks and food were included. You can stay all day but you might need to.
Detail: All the other comments posted here sound right. I went to a 19 girl mega party. The advice on finding it was helpful (button says porsche, and it is GF R) and it is right off the U-bahn. It was €88 - the €2 is for the locker. Soon in and changed. I was not sure what was going on. "Fine" was the naked barmaid. Tina (big, tattoo'd) and Begum (too skinny ... give her a bacon sandwich -not turned on by a skeleton with no arse) were being fucked in the room on the left with 5 guys watching or waiting. In the other room were 8 more guys just sitting. Two girls were in there dancing. A guy was getting a massage from another guy on the table in the room behind. Everyone seemed German. Only 5 girls including the barmaid?
I hung out in the sex room for a while, but hung back since there was no MMF going on. No rush I'll figure out what is going on. Moved back to the lounge. The spare girls didn't seem to want to join me in the sex room and didn't speak English. Still confused. No rush. Got a beer from the ultra hot Fine - shame she was the barmaid.
Eventually one of the spare girls went with me to the sex room. Ok sex with a girl I would never hire 1-1 (Yesim it may have been). Then, had a beer, chilled for a bit and a fat girl appeared and I had 20 min with her (like a moped - fun to ride but you don't want your friends to see you on one). OWO, RO, no kissing seemed the norm. Fatgirl gave another guy OWO while I had DATY - so actual party sex was
So anyway eventually I figured it out ( I think). The girls were on shifts and I had arrived during a quiet time. I stayed about 4 and half hours and other girls rolled in and out. When they are on breaks they are on breaks, so sex in the sex room. Fine the barmaid (and the best looking girl of the day) had a shift in the sexroom but by the time I noticed, she was surrounded by hogs - didn't manage to get a turn before she was back behind the bar. And she was into kissing too, darn. Some of the girls were swingers (including one who was there dancing when I arrived)- but without fluent German, I had no chance with them. There was a big swinger there reminded me of Brienne of Tarth but with bigger tits - would have done her for sure. But most of the girls were not attractive enough to get a job at TPC. So for most of a 19 girl party it is 3-4 average or so girls and 15 guys lurking about.
I had 5 sessions in the end (I said they were not hot enough for me to book 1-1, never said I was too proud to fuck them) . I really don't hang back - my closing 30 min was quite good with a 40 something slim milf with nice tits, and only a medium amount saggy. But was lots of sitting around drinking beer and talking shit to German men. Few of the girls spoke English. Next time I am in Berlin with 5 hours to kill I will go to Artemis. I really might go back to A-P at some point. Perhaps a normal day will be better. It is so cheap that there is low risk. And I want my time with Fine.
Anyway, neutral since I urge caution. Not for the faint-hearted or a new party goer.