Specifically, Google Apps can't act as a PBX replacement like Microsoft Lync and similar wares from other vendors like Cisco, he said.
"The same is true for video conferencing in Apps. You can do video chat, and the quality is ok for short, ad hoc meetings, but not for longer, scheduled boardroom types of meetings," Kerravala said.
Google Apps also lacks a full-featured Web conferencing application like Cisco's WebEx Meetings and Citrix's Go To Meeting.
Overall in UC, Apps "has limited functionality in the things it has," he added. "They have the basics down, but now they need to add the advanced features."
"They could make Apps a UC competitor," Kerravala said. "They have the installed base, they have the confidence of the consumer, which is very important in the BYOD world. But I'm not sure what Google wants Apps to be in UC and what role they want it to play in that market."
The same holds true for the Docs office productivity applications, which still can't match the features offered by Microsoft Office's Word, Excel and PowerPoint. Docs is typically used as a lightweight, browser-based complement for Office, but in response to that Microsoft now has Office Web Apps.
Office still reigns
According to a recent Forrester Research study, the most popular productivity apps suite at work is Microsoft Office 2010 (used in 85 percent of surveyed companies), followed by Office 2007 (51 percent) and Office 2003 (28 percent).
The latest edition, Office 2013, is in 22 percent of surveyed companies, while Microsoft Office for Mac 2011 is in 17 percent, followed by Google Docs (13 percent), Microsoft Office Web Apps (9 percent), OpenOffice (3 percent), LibreOffice (2 percent) and Corel WordPerfect Office and IBM Docs, each with 1 perfect.
Kerravala is among those who aren't fully convinced that Google is committed in the long term to the enterprise communication and collaboration market. "If organizations want to use Apps, they need to exercise caution," he said.
Enterprises that need full-featured UC capabilities can't rely entirely on Google Apps. "You can augment your UC strategy with Apps, but don't make it the primary focus of your UC strategy," Kerravala advised.
Alan Lepofsky, a Constellation Research analyst, is less skeptical of Google's commitment to the enterprise market. "It's a cliché to say Google doesn't know how to play in the enterprise market," he said. "It's not Microsoft, but Google knows how to do enterprise collaboration software."
Lepofsky predicts that, as it has done for Google's consumer applications and service, Google+ will become a unifying foundation for the Apps components, providing a stream of notifications and comments for actions in Docs, Gmail, Sites and other suite components.