Shuts at 1.30am I believe. Seemed to be a few taxis around the metro stop in the centre - admittedly we did set off walking to discover it was further than we thought so don't know how long the queue was.
The sound seems to be great, which is one positive. However, unless you're staying relatively near the metro stop in Madrid getting home is a pain - walk or wait 20+ mins for an Uber. Bit of a negative but hey ho!