I have installed Google Business Apps for several companies. The deciding factor for them and my company was "how will I need, and WHERE will I need to access my email, calendar, shared calendars and contacts/shared contacts"
These days, most people don't check and respond to emails from one device- the downfall from this is you will not have a record of all sent and received items.
Myself and clients check emails and calendars from work desktops, laptops, iPads and phones across all OS platforms. This products installs on all devices and pushes all email and calendar etc- so you never have lost emails, even the sent items.
It is worth it in time saved alone. The days of searching for emails is over. The shared calanders works great for my clients who are in the service or legal field.
Good luck.