Alright, what everyone said above is right on but let me summarize for the OP.
DEPENDS. It depends on how much it costs you to live and how many classes you will be teaching. If your question was truly, could I live off of teaching Kaplan? The answer is yes. Minimizes your monthly expenses and teach as many classes as you can. Could you live teaching 2 nights a week? No... But if you pick up as many classes as you can you could absolutely make enough to live. Guy I knew worked "full time" aka just taught a lot of classes and made near 40k a year...
As far as goods and bads, I'd say that overall i had a good experience. Teaching students is awesome, but I don't like having to shove the "kaplan methods" down peoples throats. Making sure you say "test day" and Kaplan methods 5 times per page gets really old...
All that to say, it is nice and I think a great part time job but I just got frustrated with the curriculum some. I think they should focus more on content and general strategies rather than 30 point Kaplan methods for everything...
Also depends on whether you use the Kaplan methods though you know? Personally I think having a "method" for verbal is stupid, I say you read it and then answer the questions. So having to spend hours talking about this strategy that I thought was stupid got old, and having to act excited about it was hard.
If you have any specific questions let me know!