Allowing your staff to use social media at work is good. It shows that you trust them. It will make them feel valued, etc.
If you encourage your employees to utilize it day-to-day, posting fun, friendly things about the company, sharing interesting articles and posts and just generally showing off how much they love their job.
If you encourage your employees to connect with each other via social media, it will actually make it easier for them to get to know each other and build relationships.
There is a chance that your employees using social media that they will waste time and go on unwanted things like replying to a message or comments.
I f your employess aren't up to date with computers, then they might get a virus without knowing about it or knowing how to delete it.
There is alwasy a chance that employees will get upset with you and decide to sabotage your business.