Pros
You can work whenever you have free time, for as long as you want. The main draw to this position for me was the flexibility.
Much of the work is repetitive, but I tend to prefer that. I find it best to find a few tasks that you can complete efficiently and cycle between them so that you don't get bored if you want to work multiple hours at a time.
Kontras
All of the work that I've been able to find that is consistently available pays well below U.S. minimum wage. The pay per hit is so low that you want to complete it fast for the work to be worth it, but then you're more likely to make mistakes. I've heard in the past that some people have made $10+ an hour, but I haven't seen anything close to that.
You can get banned for seemingly no reason at times. Thankfully, I've only received temporary bans, but it's frustrating when some of the guidelines aren't very clear, or I seem to have high accuracy and still get banned.
There are many HIT apps that are left up long after they have stopped working, so it often looks like there are more jobs available than there actually are.
The best jobs are taken so quickly that even if you found one with decent pay, it is likely to gone within an hour.