I know there are a lot of people with good nirvana experience, I am not one of them.
I got 3-4 packs of various strains from them once, and mostly these were some of the crappiest loookin' seeds, and germ rate wasn't remarkable, and there was too much variation for me. If you don't mind gettin' F2s, and you don't have a decent amount of cash for seeds, then maybe nirvana is OK. All ya really gotta do is strike gold and keep cuts from a pheno that came out great.