Pros
Depending on your country placement, you get to see beautiful new places and appreciate a different culture. Because of the various locations you might be placed, there is likely to be a town that caters to your personality and the WorldTeach administrators do their best to place you in the place of your choice and a place that matches your personality. If you like city life, you'll likely be placed in the city. If you enjoy small towns where people get to know each other, that's what you'll likely get. Some placements have more oversight for those who feel they need more direction on how to teach. Other sights have less oversight, allowing for more creativity.
Cons
Some placements might be dangerous. You could get homesick. Some locations have much less oversight, and so if you're unorganized, you might feel overwhelmed. Health care facilities can be shady in poorer locations.