I love working with the fleece. It doesn't fray after you cut it out, so you don't have to use a serger for that reason. And like someone mentioned it curls when it is stretched.
All that being said, I do serge the seams after using the patterns reccomended 5/8th seam allowance. Why?? Because it is very bulky and this takes it down to a manageable seam and the finished look is nicer. I sometimes grade the seams, depending on the garment and whether there will be an intersecting seam to be sewn afterwards.
I use a longer stitch length (3) and a denium needle. This stuff is thick! So if you are doing a top stitch, buy a top stitch thread, otherwise is gets burried in the fleece.