If you don't plan on paying for Microsoft Office on every desktop, the relative benefits of the two packages changes considerably. It's much easier to use Office 365 with the (free) Office Web Apps, and to use Google Apps for Business with the (free) online Google Docs, so any evaluation of the relative merits of Office 365 and Google Apps has to take into account the features in Office Web Apps vs. the online Google Docs.
That's problematic, as the online versions of Word, Excel, OneNote and PowerPoint -- as well as Google's online word processor, spreadsheet and slide show programs -- are changing constantly. For example, Office Web Apps added a "rint function to Excel just last month.
On balance, Office 365 gets an 9 for features, and Google Apps a 7 -- assuming you will work in an environment with some version of Microsoft Office on every desktop.
Ease of use: Familiarity breeds comfortWhen you're talking about ease of use from the end user standpoint, Microsoft has an unfair advantage. When users encounter an Office alternative, they're not likely to appreciate some upstart's attempt to reinvent the UI (Microsoft has done enough of that already).
So the burden is on Google Apps to create an inviting user experience, and for the most part users will find it a snap to learn their way around the core apps and get productive -- and with fewer features, there's less to learn. But there's one major hurdle: Gmail. We can debate the relative merits of Outlook (or OWA) and Gmail forever, but for the typical user who has invested months of blood, sweat and tears on learning Outlook, the transition to Gmail can be traumatic.
The Gmail interface is completely different, whereas the latest version of Outlook Web Access (see Figure 3) pretty closely resembles Outlook on the desktop. Gmail (see Figure 4) packs a lot more information into a smaller area and puts the most common functions in completely different places. Advanced users may prefer the Gmail layout, but most others will prefer the devil they know.