I've seen every episdode of MM and like most of us here, think The Sopranos is among the best examples of art in US popular culture, so I will give you my take.
I have not seen all of the heralded shows that are on the air today, but from what I've seen, MM seems to be the most obvious spirtual predecessor to The Sopranos. And it's not only because of the pedigree with Matthew Weiner, and many of the crew/directors that worked on both shows. MM seems to be addressing many of the same existential themes that guided the Sopranos.
MM is a very good show. It is very well-written and for the most part, very well acted. It is a period piece that seems to nail every detail of life in the 60s, and is very honest and at times brutal in its depicition of these character's lives.
If The Sopranos was a "10", Mad Men is a solid "8", sometimes a "9". Critical opinion, however, has been fairly overblown to the point that if MM retains some level of consistency, many will rank it above The Sopranos, IMHO.
Still, I would recommend it to just about anybody.