The second great thing about it is your mortgage payments will be really smaller.
The third thing that is great about this is that when you are finished paying off your mortgage, you won't have paid 3 times the price of the house in interest. I say, go for it!
Offering half as a down payment may make the offer more attractive if there are multiple offers and the other offers are putting less down but there is no direct correlation to purchase price. Make your offer based on recent comparable sales. Your agent will help you with this.