For me a "good" relationship is one where I feel that I can be myself and not have to hide. I love the feeling of "meshing" with someone's where I feel that I am an important part in their life (and they in mine). I love feeling like I can trust and be trusted.
I am far from an NRE addict - while I enjoy it, I like it just as much once the initial fumbling and exploring settles into really getting down to enjoying the other. I want to feel intensity - it should be exciting - whether after a month, a year, or ten years.
And I think I consider a relationship good when it meshes with my other relationships, whether significant others or friends.
"Listen, or your tongue will make you deaf." - Native American Proverb