My Take
My overall opinion about padlet is that it is a great teaching tool. It is an ongoing discussion of the topic you are talking about. Students feed off each other and share their information. The students grow on each other's ideas. I like that you can only see the page and share your ideas if you shared the link with other people, so no one can go on the page unless they have the link. The downside of padlet is that sometimes students will write silly things on the other students page and they sometimes use it for their personal communication tool within the group rather than school related purposes.
How I Use It
I use padlet when my students are working in book clubs. Each book club has there own padlet page and they post their discussions, pictures, questions, summaries, etc. I comment or give feedback on their discussion board. They use it in class when they meet in their book clubs but also at home when they have to do their homework. It's a great communication tool for the students within the book club but also between the students and the teacher.