I have used this service for my client's data labeling, it was very easy to use with great support team who is always willing help me solve any issues that came up throughout project lifecycle of label creation process from design phase through final delivery stage.
They also provide excellent after sales services which made our experience seamless even though we were located in different time zones! We didn't face any issue during implementation or post-production stages as well so there are no downsides at all here!! Highly recommended if you want quality work done without having much hassle attached along side your existing workflow/processes then definitely go ahead. Great customer care provided too!! The only thing i can think about would be more detailed documentation regarding their product features but they do offer free trial period where one could check out its functionality before making decision whether purchase license should happen afterwards! So far everything has been working.