What does Skype for Business do well? Skype is a very well-used business communication platform. It does call very reliably, and the chat option is robust as well. Skype is great for it's consistency.
What does Skype for Business not do well? It doesn't have a ton of fancy features, and it's integration options aren't as extensive as those of it's competitors (like Slack)
What do you wish you had known about Skype for Business before using? If you need really good quality video calls, then Skype is great. If you need more chat functionality, then other options may work better for your needs.
Have you used a competitor to Skype for Business? If so, how does it compare? I've used WebEx, Zoom, and Slack. Slack is great for the messaging, and WebEx and Zoom do calls fairly well, but Skype handles both well enough.