The tool provides an excellent platform for internal communication, which has been very helpful in our daily work routine! I can't say that there are any downsides at this time as we have only used it since its launch, but if you want something like Slack or HipChat then try both out before making your decision - they're great tools too, just not quite what we need right now (as far as features go).
We use IVCI internally when working remotely with clients across multiple countries so having all staff members able to communicate quickly was essential to us from day one. It's helped eliminate some manual processes such as emailing files back & forth between offices etc., ensuring everyone knows exactly where things stand on projects.