It is safe for the seller as a money order is considered cash by the bank and therefore can't "bounce". However it provides no security for the buyer as once it is cashed you can't get you money back even if you get no product.
If you are talking about security for the buyer you gotta put it on you credit card that way you can reverse the charges if you don't get it. If the seller can't do credit cards then do it through paypal.
Proud Owner of:
1.0 Chinese Water Dragon (Timon), 1.0 cat (Maxwell), 1.1 Leos, 0.0.1 Pacman Frogs. Always expanding.