Blockchain is a buzzword describing the current excitement for an innovative technology that could change and disrupt major industries and economic sectors. Blockchain technology has the promise to change all existing business models and make financial services cheaper contributing therefore to a better financial inclusion and, even a better economic wealth distribution. Numerous studies optimistically praise such potential societal benefits by listing all processes that could be optimized through this technology. However, the picture is not necessary all bright. Blockchain can indeed disrupt and significantly improve our societies but there still exist some societal costs in the way this technology is implemented. This paper provides a perspective overviewing of the current trends related to the development of the most widely used implementation of blockchain technology based on the proof-of-work consensus algorithm. These trends will be discussed in three steps: the ‘Good Blockchain’ overviews how this technology can improve our societies; the ‘Bad blockchain’ offers a more nuanced perspective by discussing the potential polluting activities generated by some mining activities. Finally, the ‘Ugly blockchain’ investigates how this technology might generate a risk of concentration in the mining industry affecting therefore the nature and even the existence of the blockchain technology.