Excellent!!! Made it exactly as written and plan on making it again and again!
My wife really liked the recipe. We don't have mayo in the house though and I substituted plain lowfat yogurt. This added a nice sourness to the the dijon mix and makes it a bit healthier. I also found that I had to cook the fillets longer...about 20 min.
I would suggest reducing the amount of mayonnaise to 1/3 cup. I had medium-sized filets, and they took 20 minutes total just to cook through.