Hirhurim linked to 2 articles by R. Yitzchak Breitowitz (Torah and Professionalism and Choosing a Profession: Torah Considerations) which compare the good and bad points of learning in kollel vs working. It is definately worth reading.
He left out some important negatives of kollel.
1. The wife has to work full time to support the husband, meaning she has to go out in the world, not kol kevuda bas melech pnima. In addition, the children end up being brought up by the babysitter.
2. It places a tremendous burden on the parents, the parents need to support the young couple while he is sitting and learning.