If that is still connected to the supply, it's dangerous, as there are exposed wires and an open junction box.
However it may not be in use any more, looks like parts of old downlights which have just been left there.
Deserves it's own post in the "DIY Disasters" section.
I blame Sarah Beeney for all this expert property development work we see these days (and Lawrence Llewelyn-Bowen for the stunning design ideas we see so much of)[/sarcasm]