I've used vistaprint once. The product was good, but yeah, don't use their design templates because the final product won't be particularly original.
Another word of warning. They are very good at marketing. I too was drawn in by their advert for 250 free business cards, but that is for a very thin type of card and not really a good product. They are very good at upselling you to a better, more expensive product and before you know it, you've spent $50 on your "free" business cards lol.
They are much cheaper than high-street printers though for an equivalent product / service.