I, personally, didn't find the outlet stores worth the time it took to drive out to them. Some of the merchandise was the same price as on property. Most of the merchandise was dated or from past events. They had the year "2003" on them or they were from the marathon (we went in Feb and the marathon was in Jan).
If you're desperate to save a few bucks, are ok with burning the time, and don't mind dated merchandise, then the outlets are for you.
As for me, I won't burn valuable park time traveling to the outlets again.