I saw them live a bunch of times during the grunge days and they weren't that great live. Other than Dave Grohl and Dale Crover Nirvana didn't have that much talent. Even years after he blew off his drugged out head there were people wearing smelly sweaters at the 5 point bar crying about Kurt.
If you like Nirvana check out the Melvins or anything the King Buzzo plays in, Buzzo pretty much started Nirvana.