The ease of use, the documentation that makes it easy to understand how things work at first glance (and then you realize there are 100s of options!), the fact its just so fast! There's nothing I dislike about cloudmersive as such - but this isn't really an issue for me since its been great from day 1.
It has allowed our team to rapidly develop applications without having to worry too much about infrastructure or platform choice, leaving us free up time to focus on writing code rather than managing our infrastructure.