You know, when anyone knocks on my door trying to sell meat I find it suspicious. Perhaps your experience was better. I kid, but I looked at their site and they give little reason why one ought to order from them over going to, say, WholeFoods, or, even--considering their site's Manly-Man aesthetic--Giant.
I only order meats from D'Artagnan, or have Dean and Deluca order for me (or Ely's Meats at the DC Farmer's Market) when I need something uncommon like quail, foie gras, or Wild Boar--as someone else was looking for on another thread.
I guess they're worth a try, but they're neither cheap nor particularly appetizing.
Let us know how they are if you do try them out.