If you must simultaneously edit documents on a project, Huddle is not a good option. Also, if your team is not technically savvy, the learning curve can be challenging. Finally, if you need hundreds or thousands of people working on a project, Huddle might not be the right choice. I think it is better for teams under 100 people.
The desktop app is occasionally unreliable and it is never easy to get to the bottom of it with the tech support people...
Tasks are virtually useless as they have no context. We want tasks to be against documents so we can make our workflow more formal but they are not, so we don't use them. A reimplementation of to do and calendar facilities with files/documents as the context would make a huge difference to us.
The Huddle Office plugins are a great idea, but they cause us far too many Word and Excel crashes so we have to turn them off.
Huddle is very easy to use whether you are a new user or you have used it for years, it is an incredibly intuitive system that is so simple to teach to new users, the lock feature prevents important documents from being edited accidentally, while the edit features allow for true collaborative working
Oh Slack is more expensive and Huddle gets exactly what we need done, not much to say other than they have proven themselves and we can go confidently with them knowing if there's an issue we'll get the support we need