We use Skype for Business at work, however when the boss isn't watching we switch to appear.in since it works much better and doesn't require craptastic software.
SfB is pants. Quality is always crap, UI is terrible, Mac client is constantly behind, there is no really-open interface for Linux and bots, etc etc.
But, the boss will see when you're "available" straight from Outlook, which is where he lives. It's not an IM tool, it's (yet another) instrument of workforce control.
Don't even get me started on the mac client... constantly drops calls, other end complains that sound quality is terrible despite high quality headphones, screen sharing stops suddenly mid presentation, can't see scheduled meeting directly in app, and overall horrible UX.
Also, despite the rigid security policy where I work, the mac client stores my password in the keychain.