Is the frequent sudden death among one of the signs of the Day of Judgement? Is it considered something good?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.

Sudden death is one of the signs indicating that the Last Hour is near. The evidence is that Anas narrated that the Prophet said: "Among the signs that the Last Hour is near, is that the crescent would appear larger than its actual size and people would say: “It appears as if it is only two days old.”, and the mosques will be taken as streets, and sudden death will spread.” [Al-Albaani classified it as authentic]

As regards your question whether or not it is a good sign, the answer is that this differs according to the dead person. For a believer and an obedient person, it is good for him, but it is not good for a non-Muslim and a disobedient person. ‘Aa’ishah narrated that the Prophet said: "Sudden death is a rest for a believer, and a sorrow for a non-Muslim.” [Ahmad]

Allaah Knows best.