In reply to Hotbad Peteel:
+ve
more social - group of you can chat / take piss / offer mild encouragement while one climbs
get much more done than routing (the way i clmb routes anyway) especially for summer evenings
helps practice footwork / confidence for when you do proper climbing
cheaper to start
-ve
not proper climbing
not as exciting
silly hats when its not cold
Summary -
Theres a time and a place.