The coin has to be useful if there is already something that can replace it - the coin won't last. Next, you need to make sure that the team behind the coin is reliable, search their LinkedIn, landing page and find out whether they have an expertise and have been involved with the technology they are using. Also, google them and make sure they don't have any scamming records. Last but not least, make sure that their product gives a new solution if there is already a steady centralized project that can solve the problem, what's the point of decentralization?