If you're a basher, it's gotta be worth doing imo. It does add quite a bit of weight to the shell, and isn't that cheap. 1 big tube should be enough, 2 big tubes will do a great job. But compared to smashing a shell on every bash, it's worth it :-) There's a guide on youtube. If you can get a friend to help it makes it a lot easier. He can measure and cut the tape the size, while you smear the goo around with your fingers. Spread a load of goo on, stick the tape on, spread more goo over the top and layer as necessary. This isn't for looks though. The mesh and goo can show through the paint a little, and is bound to get on the outside in places. But looks aren't important to me.
Here's a pic of my truggy shell for inspiration :-) It was cracked through from the single rear body post, but the goo has made it stronger than new.