Well, I just created a Drupal Gardens website and it seems pretty cool. I like the fact that they are pre-installed modules, themes, content types, blocks, and other helpful things to get you started with the website. One of the downfalls of Drupal Gardens is that it seems very limited in a way. From the first look, it seems like there isn't a option for a user to install their own modules. I guess that the main purpose of Drupal Gardens is to give first time users some experience with Drupal and guide them through the different features.