The city has some interesting sites to visit (the new library, catacombs, mosque, citadel), but the infrastructure is crumbling (no police, no garbage collection). We did not feel at all unsafe, but if the infrastructure and social order keep going down it could become an unsafe place in short order.
We were there on a Sunday. Malta has a lot to offer, but unfortunately a lot is closed on Sundays. This was our second cruise visit to Malta (and second time on a Sunday, how unlucky can we get?) but we still found a lot to stay busy and a lot to see. Their antiquities are absolutely amazing.
We docked at Aghios Nikolaos, where the port is right next to downtown. We did not spend much time in AN, instead rented a car (there are numerous car rental agencies right outside the port, Hertz is the closest) and went to Knossos ad Spinalonga, Knossos is nice but way too crowded in the summer.