I have used uShip to send things 5 times now over two years- everything from my dog to a 2004 Accord to my son's entire apartment.
It is a terrific site that empowers consumers to save a lot of money while also providing smaller transportations companies the ability to make money filling excess capacity.
Is it failsafe? No. You must follow commonsense - If you insist on taking the absolute dirt cheapest bid from someone with zero or worse feedback and then you stupidely send them wire transfers of money before they do anything - yeah you might not have a great experience (duh!).
If you are not a cheapscape, get a contract, only use a credit card, and always review feedback, you will be fine. Most of these complainers fall into the first category (or they are competitors trying to win business away from uShip). Just apply some commonsense and you will find uShip to be one of the best sites on the internet.