The biggest drawback to using Google Wave in its current preview version isn't what's there, but rather what's not there -- direct communication to the outside world. For a service built for communication, it's surprising how much of an island Google Wave is -- it doesn't even integrate with Gmail, much less other mail clients and services. There also are no links to social networking sites or instant messaging tools -- not even Google Talk.
For example, your list of contacts in Google Wave is entirely separate from your list of contacts in Gmail. Worse yet, when you click Manage Contacts in Google Wave, you don't even get to manage your Google Wave contacts. Instead, you get sent to Google Contacts, a list of your Gmail contacts, which doesn't include your Google Wave contacts. Eventually, Google will hopefully integrate Google Wave with Google Contacts. But given that Google Contacts is in beta and Google Wave is in preview, it's not at all clear when or if that will happen.
In other words, to be truly useful, Google Wave needs better integration with other services. For example, you should be able to start a wave directly from Gmail with other Gmail users who also use Google Wave. You should also be able to see your Gmail contacts from within Google Wave and send them an e-mail message using Gmail. And you should be able to start Google waves with your contacts on social networking sites. None of these things are currently possible.
The bottom line
There's no doubt that Google Wave is an innovative tool for real-time group communication. Spend a little time with it, and you'll most likely begin to want to use it. But it doesn't solve the biggest problem with Internet communications -- their fractured nature.
People use a variety of e-mail systems, a range of social networking sites, different chat clients ... the list is a long one. There are too many ways to communicate, and no way to integrate them all. In fact, Google Wave makes the problem worse because it's adding yet another way for people to communicate without integrating other services.
Some observers believe that Google's eventual goal is to have Wave replace all those services. But no matter how grand Google's ambitions may be, hundreds of millions of people around the world are not going to desert the way they communicate. Abandoning their current e-mail and social networking tools would be far too disruptive to their work and personal lives. What's more, Google Wave doesn't have the kind of social networking features that are built into sites like Facebook, and it's not designed to replace them. At this point, Wave is only an adjunct to those services, best suited for very specific projects that require live (or close to live) collaboration.