That's the whole story, but it's a smart one. On standard shopping engines, like NexTag, PriceGrabber, and MySimon, you're given prices for single products (or boxes of products). Many consumer items are bought in multiples, though, and Tjoos' crawler deciphers the quantity discounts in the sites it covers.
Even for items that aren't usually sold in quantity (digital cameras, for example), the addition of store-specific discount codes to the pricing engine can make a fundamental difference for users. Other shopping engines don't pick up coupon discounts.
Tjoos reminds me a bit of Farecast (more), as it gives buyers a better overall picture of the market they're in. Tjoos doesn't show the quantities where the discounts kick in, though, which would make shopping for the best value a bit easier. It's still a neat idea.
In this early release, Tjoos only scans for prices on contact lenses. More product categories will be added later.