The 4 stars is because of the risk of severe steam burns.  I am not a careless person, but when I took the lid off to brown the bread I got 3rd degree burns on 3 fingers from the steam that escaped as soon as you started to lift the bowl.    5 days later I still have huge blisters.  The bread actually had a light golden crust at that point so taking the lid off might not be necessary.
5 stars for the function of the bowl and lid,  While I will miss the wooden bowl for rising and this bowl needs to be cleaned between steps, overall it is a great product. ( read instructions completely, not a one step bowl)  It does not make a huge loaf so if you have a large family this isn't practical.  The recipe that comes with it makes a nice tender loaf.