I don't own a Jacksons chameleon but i have heard that they required very specific care i.e. misting systems and such. I have a Veiled Chameleon and would recomend one of these as a beginner chameleon. Chameleons are a whole different lizard. The most common problem encountered with chameleons is dehydration. Since they don't drink from a bowl they depend on other sources like water dripping on leaves and they also get moisture from the food that they eat. It is also important that you give the crickets food that will keep them full and hydrated. But both these animals do very well in captivity if given the correct conditions. But i have to stress that getting your Chameleon from a reputable breeder or supply store.

Here is an exelent caresheet on Veiled Chameleons.
http://www.kingsnake.com/rockymounta.../RMHveiled.htm
Here is an very good site on Jackson's Chameleons.
http://www.kingsnake.com/rockymounta.../RMHveiled.htm