Working in sales always has its ups and downs. There's not a huge variety of products to sell, so I've seen some people burn out due to having the sames convos over and over again. Having said that its not a hard product to sell, so if you can stay focused you have the ability to make decent money.
Sometime the dial-er will cycle through old leads, and you can be forced to speak with people who are no longer looking for work. However most of the time the leads are great.