Let's not mince words: this is food for stoners and latchkey children. If you need a peanut butter and chocolate fix RIGHT NOW but your dorm room doesn't have an oven and you don't own your own eight inch square pan, or if your parents let you use the microwave but not the stove, then this is the treat for you.
Any time a dessert mix comes with its own pan, you're kind of in trouble. I say "kind of" because this sort of thing certainly has its place. I remember when I was starting out, my first year in college, I had access to a stove but I didn't have any kitchenware. Nor did I have any money to buy some. (If I knew then what I know now, I would have just gone to a thrift store and bought a bunch of stuff, because "used" Pyrex dishes really are perfectly fine.)
I also had some hippie roommates who loved to make pot brownies, but weren't really capable, organizationally speaking, of making them from scratch. By the time they decided to make a batch, they were usually at least two sheets to the wind. They and their philosophical brethren are no doubt almost single-handedly responsible for keeping the "brownie mix that doesn't require an egg and comes with its own baking dish and all you have to do is microwave it" industry thriving.
So I feel that it's only fair to evaluate Reese's Dessert Bar Mix by those standards. The problem is that the more convenience you offer, the less deliciousness (as measured on any objective, non-high scale). Otherwise the stuff would cost twenty bucks a box. This box set me back the princely sum of $1.48 on sale.
Do I feel that I got my $1.48 worth? I do.
Would I buy it again? Probably not.
The peanut butter is good, if overly salty. You mix it with some peanut butter-flavored cake mix powder, which gives it the requisite crumbly, gritty texture. I have no beef with the chocolate crumb crust. But the "chocolaty" topping is too thin, tastes extremely fake, and has a strange taupe-y cast to the color.
The end result is something which tastes mostly salty, some sweet, peanut-buttery, and - a distant fourth - like an approximation of chocolate.