Pros
Easy work. I have been doing it on and off for 5+ years. You can do it while watching TV and doesn't usually require a lot of time or effort as a skilled writer (unless you choose to accept some of the more lengthy work that is available occasionally). Work is completely flexible. You only have to do the writing that you accept. There's a good variety of topics, so you can write about what interests you or explore something new to hone your knowledge and ability.
Kontras
Pay is very low and the income is not reliable. Gigs usually pay anywhere from $4-$20 depending on the length. Around $4 for 200 words, $20 for 800 words. Clients get 30 days to approve work. If they have edits, they get another 30 days, so you can go MONTHS without getting paid if you have a picky client, and the pay is nothing to write home about anyway. It's beer money, at best. I would not recommend this site to someone who is trying to find work to make a living unless other opportunities are dried up for the day.
The briefs are usually not detailed, so it can be especially difficult to write about a topic if you're not as familiar with the subject matter. It is like the people who own the site have no understanding of what it is like to be a freelance writer.
You usually only get a few hours to write depending on the length of the article, and work will be unassigned and put back in the queue if you pass the deadline. You really have to prioritize the writing at the time you choose to take it even if the briefs are minimal and the pay is low.