Pros:

• Some chameleons love to drink out of ponds if there are air bubbles (created by an air pump, costing under $10!). Without air bubbles chances are a chameleon will not respond to still water.
  
  
• They are esthetically pleasing.
  
  
• If you do have a pond, make sure it is swallow to prevent your chameleon from drowning. I suggest gluing a couple of thin sticks across the pond to give your chameleon something to grab onto, making it easier to get out of AND placing a large rock in the pond.

Cons:

• A pond develops a slimy ring very quickly and if it is not cleaned regularly it can become unhealthy.
  
  
• Difficult to change water if it's connected to a "reptile hammock" (popular type of pond).
  
  
• Bugs drowned daily.
  
  
• Chameleons tend to go to the bathroom in water.
  
  
• The air pump can be quite loud, air stones must be changes monthly (they dissolve and get clogged with sediments).
  
  
• There is a risk of your chameleon drowning. Do not use a pond if you have a weak chameleon, as it may not be able to pull itself out of the water if it accidentally falls in.
  
  
• For some reason my chameleons always got very relaxed in the ponds, and I caught one of mine so relaxed, that his head was submerged, and eyes closed! Luckily I was there to pull them to safety.