Brandenburger Tor is one of the nicer metro stations I visited on my trip to Berlin, as you can…read moretell with the name it serves the Brandenburger Tor which is basically the Brandenburg Gate which is one of the main and key attractions in Berlin.
It is located on the U55 line which is quite useful for connections into Bundestag and Berlin Central Station, the overall journey across the line from Brandenburger Tor to the Hauptbanhof (Central Station) is 8 minutes and as I recall, this is the only line this station is on, meaning most likely you're going to have to visit another train station to change, being one of those two, to get the metro into Brandenburger Tor, perhaps because of this, it might just be easier to get the bus as I found to be easier when traveling from my Hotel.
I called at this station by chance, hoping to get into Central Station so I used the U55 line to go the full length of the train route which is 8 minutes.
There did appear to be one end of the station cornered off, which probably was the place you would get off the train for the U55 here at Brandenburger Tor, so they appeared to be turning and using the other plaform for some reason.
This metro station did also seem bright and modern, it didn't seem old, dark and smelly like some trains on the network and also had lift access, warranting a solid three star rating which is supported by the location being meters away from the Brandenburg Gate.
3 star rating due to reasons discussed above, sadly I don't feel it is worth any higher as the station remains understaffed and of course it is only on the U55 line.