None at all really, it is honestly as easy as I make it sound :)
It scribes like hard plastic, better than Milliput in my opinion as I've always found Milliput to be a little prone to flaking and chipping as I try to scribe it. The only real gotcha is the possibility for fumes, as some people are sensitive to the fumes from super glue. If I'm doing a big load I do sometimes use my spray booth to avoid breathing too much of it in.
Another way of using gloop is actually as glue. I sometimes mix up a batch and glue my parts together with it. The stuff that squeezes out of the joint can be wiped smoothish, or just left to dry as it is. Once it is dry, sand it away and you're done! Glued and filled in one easy step :)