The Google Apps email can be set up with iPhones, Androids, Blackberries and most other common mobile or tablet devices.
Please note that we do not provide tech support for your devices as we are a web services provider, and on-site tech support is not our realm, much similar to a Cable TV company not being responsible on how to hook up your sound system to the cable box.
iPhones & iPads (iOS devices):
Instructions from Google: https://support.google.com/a/users/answer/2365095?hl=en
Instructions from RIM: http://support.blackberry.com/kb/articleDetail?language=English&articleNumber=000033472
For other device instructions, please open your Google Apps email on your computer or laptop, and go to Settings -> Forwarding/POP/IMAP tab, and look at the bottom of the screen for setup instructions for different devices.