This has to be one of the best inventions for first time breast-feeders!  It helps support the baby and get her at the right level so that mom can use both hands to get the rest of the activity squared away (which can be a real challenge at first!).  It is especially helpful for the 'football hold' which is how I fed my daughter for the first few weeks. 

After a while I found that the boppy was more of a nuisance to use while breastfeeding than as a helpful support, so now I use it to prop up my baby.  She can face forward on it (in a modified version of tummy time) or more often I lay her...