RingCentral allows a far-flung Internet-based company to act like a local company in terms of having a local number to call (and call from), while allowing you to quickly and flawlessly transfer callers between extensions even if those extensions are on opposite sides of the planet. It also records all of your texts and calls, allowing you to download and save them for future needs, which is vital in any litigation-sensitive business like property management.
On the level of an individual worker, the ability to mix and match a SoftPhone (on your PC), the RingCentral app (on your mobile device), plus seamlessly forward calls from your landline *and* make a VoiP call that then forwards *your end* of that call to your landline and allows you to have the conversation over the phone like normal.
Really, the only problem with RingCentral is the price. The price per person per month is steep enough that a smaller company has to really be careful with who they give extensions to, and the limitation to two SoftPhone installs per extension means you can't really use an extension for a whole department or team. Right now, for example, my Marketing team has 3 full-time and 1 part-time worker, but the company can only afford one extension for all of the marketing, so I can't even install a SoftPhone on my desktop and my laptop, because the other one of our SoftPhones is installed on a computer in the Philippines so that we have multiple people who can answer the phone in case one is busy.
Oh, and I have had occasional problems where texting a RingCentral number from a service like Google Voice will flat-out not work, and we can't figure out why. But that's a really minor complaint, all things considered. :)