Connecting an Apps account appears to be a simple affair, most of the steps are the same as for connecting a regular Gmail account. The only difference is using your full email address rather than a Gmail username.
As Evolution is not a supported client, I used the generic instructions. This only includes instructions for setting up POP, which I've disabled on my account. When enabling IMAP connections for my account, the web interface rather helpfully informed me that I need to use "imap.gmail.com" as a server. Armed with this knowledge I set Evolution to use IMAP+ (I've heard that gmail supports push email with IMAP) and continued. Please not that security settings are SSL (not TLS) and Password rather than PLAIN for authentication.
The tricky part for me is that I'm using 2 factor authentication on my account. First step for this is to create an application specific password, this can then be used in place of your regular password when setting up the connection.
|Generating an application specific password
Calendars are proving a little more tricky to get going. By default, evolution creates a single calendar, which appears not to be connected to anything. The partial solution I've found is to manually add each calendar. Because the the infernal 2 factor authentication (starting to regret setting it up now!) I'm having to keep the application specific password on hand as I need it to retrieve my calendar list and add the appropriate calendar.
This all went well until adding the 3rd calendar. At this point it refused to allow me to add the calendar, despite having all the appropriate details entered. Can't be a bad password as it allowed me to view the friggin calendar list! At first I suspected this was some kind of limit. So I deleted calendar #2, can't add it again! I can add local calendars but not Google ones. Very useful!
After a few more attempts I found it was being temperamental - sometimes allowing me to add a calendar and sometimes now. Finally, I think I've figured it out. If I don't enter a name to give this calendar, before retrieving the list from Google - it won't let me add it. Specify a name first (even a temporary one) - it can be added. How strange is that?
The only other "quirk" I've noticed is that my default colour selection is overridden when a new calendar is added. Going back in to change the colour will commit my ACTUAL selection. Annoying, but not a deal breaker.
|At long last, calendars!
Don't check the box marked "Mark as default calendar" - I did this with my main calendar and no entries showed up in GNOME. I could be wrong, but changing this setting seemed to help.
|Default Calendar - Caused me troubles!
The end result - I can now get my notifications on my desktop.
Something particularly useful is that selecting the current day will let you see your schedule for the week along with that days events.
I don't see this as a replacement for the web interface. I see this more like my Android phone, it's another tool to complement it. The web interface is very useful for when I need access to my calendars when I haven't got my phone with me. My phone and GNOME are great for providing notifications.
I'm going to need to use this intensively for a while before I can say for sure whether I'll continue using this and how useful I think it is. It's certainly much more of a faff to set up than an Android device.