If by healthy, they're as healthy as any big hatchery chicken would turn out to be, but by the standard for the breed - Most of the time, no. Your chickens won't turn out to look like their illustrations (but the illustrations show would they would look like if they weren't from a hatchery) The chicks from there have been bred for egg laying, so most won't be as big, fluffy, or well colored/patterned as should be by the Standard of Perfection.
But, as simple pets, they're great, however I have indeed come across several birds from them with issues. (eggbound hens, deformed backs, crooked toes) however if it happened too often, McMurray wouldn't last as long as a business as it has been.
I've never ordered from Murray McMurray but that company is favored by Martha Stewart. She gets her chicks from Murray McMurray and she has a really significant number of chickens of all sorts of breeds.
Just thought I'd throw that out - I am not a Martha Stewart fan but I did watch the show where she featured chickens (and several BYC members were invited to the show taping, as was I, but I could not attend). That may sound like I'm a fan, but I was only interested as a home chicken keeper.