It’s very simple but also has many features like multiple payment methods (bitcoin/usd) along with various countries which makes this an excellent choice if you need international transfers in short notice without having to rely too much on third parties such as Western Union etc.
For transactions that are not instant there's always some waiting before funds reach their destination so make sure what exactly needs transferring ASAP! I can't think of any complaints at all really? Maybe they could improve certain aspects by adding more details about transaction fees though sometimes they're quite high compared to other providers.