Actually i bought some for my son but never ended up using them! They are ridiculously expensive and more to the point, not that helpful. After buying them, I was advised to use the really thin toddler panties instead (you can get cheap ones in the lanes). That way, the child is aware that he/she is wet. Helps to reinforce the potty training.
Anyway, the training pants are just super thick panties which 1) still doesn't prevent leakage and 2) takes forever to dry. Plus with the super thin cheapie panties, if there's a bad accident while out, you can just throw them away without too much of a pang (the panties i bought ended up costing less than disposable diapers in terms of cost per pair!).