I like that there are multiple options available for different companies at various price points with varying functionality (e.g., some offer only carrier tracking while others also have parcel pick up options).
There's no way of seeing what your current rate will be before you set it in their system - which can lead people into thinking they're getting too low when actually doing so could cost them more than necessary. They don't track carriers all over North America either - this would make things easier if someone wanted service outside of New York City or Toronto area where we do business. We use an integration between our platform & theirs because otherwise setting rates/packages was time consuming.