What does Buffer do well? It's a good, low cost option, and has a very clean interface. It's also probably the simplest tool to set up and use. I also like that it has image editing and video uploading. And there are lots of resources (blog, emails, guides, webinars, FAQs) to help you get better, and to answer questions.
What does Buffer not do well? It's less impressive than some of the others out there. It also doesn't have categories, which is helpful for segmenting your content. It also doesn't have much by way of analytics or varied plans for different needs. And, ultimately, the reason it doesn't make the top of my list is that there is no recycling or auto scheduling.
What do you wish you had known about Buffer before using? Nothing. It's a great tool for the right person. People who have simple, straight-forward needs will be pleased.
Have you used a competitor to Buffer? If so, how does it compare? I've used Buffer on three different occasions. First, at the nonprofit I used to work for. Second, for the nonprofit I used to volunteer for. And, third, for my own business, mostly for scheduling Facebook Group posts, before that was possible in FB itself. Now, it's just a handy tool to have as needed. It's a solid option, and very easy to use. However, for my needs, I went with Smarterqueue because it recycled posts automatically and had more features I was looking for. But depending on your needs, Buffer could be a great choice.