@chilimatic has given an appreciable abstract viewpoint. One important point I think when you are on the verge of selecting NoSQL vs SQL is to ask the question, if you have to do a lot of "transactions".
I don't know about other NoSQL databases, but from what I have come to know; the NoSQL solutions' support for transactions is squeamy at best. That is why I never feel at home when I have to deal with NoSQL thingies, they propose "entities-isolated" way of thinking.
Being an old guy, you can feel right at home with SQL, if you have to deal with a lot of transactions.
I might not have the whole picture here, so please feel free to elucidate the old guy. :)