Pros
LitCharts is a great deal for freelance writers and English/humanities graduates--it's very flexible, it pays well for your time compared to other freelance jobs, and the guides are fun to write. (You often get to choose your texts, so I've chosen books I've wanted to read or that I'm otherwise working on--I'm a grad student--which makes the work feel more enjoyable and productive.) The team has been very accommodating of my schedule and allowed me to set my own deadlines, which is great if you're working on multiple projects or have other commitments.
Cons
There is a learning curve at the beginning in terms of figuring out the format, stylistic conventions, particular ways of arguing and thinking about literature, etc. So I definitely spent more time on earlier projects and had more revisions to do. But I found this decreased a lot as I went on--and the editors are really helpful and responsive.