Crowded: no, you can almost always find a place to seat. Paris PT is crowded, not Berlin's. Unreliable: true for the S-Bahn, outages are frequent. All things

Crowded: no, you can almost always find a place to seat. Paris PT is crowded, not Berlin's. Unreliable: true for the S-Bahn, outages are frequent. All things considered, it's still better than all other big cities I have visited.