Pros
Very little pros, besides usually a variety of assignments to choose from daily (requesters often won't even accept the article.. see cons). The pay is about $7-$8 per hour, and that is if you slam out a $3.90 500 word article back to back. This is for Premium level which is what I was graded at, standard it's even lower. For a 1000 word article the pay is about $7.98. If you are in North America, UK, Australia or basically any developed country, the pay is unacceptable and I promise you will GRIND away for even $20 a day on here. Are you a freelancer in Thailand or some other place your money goes way further? Maybe it will be more worth it for you.
Cons
Cons are obvious, extremely paltry pay (less than $5) per article and often the requester gives very long instructions (yep, you'll work very hard for that $3.90) which further cuts into your hourly earnings.. even if your writing is high quality and you have experience (as in, you KNOW your writing is up to par) the clients can reject your hard work and are entitled to not give a reason.. thus you might not see a dime. Let's not even get into revisions and the fact that it's not unheard of for clients to still use articles they rejected, which is theft.