>Slack's only real threat, IMHO, is Whatsapp. Whatsapp has a brilliant mobile experience which works offline too - Slack is weak there and I don't know why they can't have a mobile app that works properly offline. With Whatsapp coming to desktop (although via a mobile go-through), whatsapp is suddenly a bit more usable for a team.

The main reason for me. For switching from Whatsapp to Slack was because I completely suck at typing on a mobile phone. I type 150 wpm on my mechanical keyboard but typing a single sentence without typos on my mobile phone? No can do.

I heard a lot about Slack from Reddit/HN. I gave it a try and haven't looked back since. I'm a student and we use it for a kind of personal facebook group. It's great. If you are in uni I highly suggest you try it out.