iPad is 'that' hard because it is non-trivial to take advantage of the new screen real estate. Often-times you must implement a completely new navigation model because the stock split view controller is rarely the navigation model you want to use.
iPod touch is generally easier. It usually comes down to gracefully degrading features. Much care must also be taken to ensure that the app performs well on the iPod touch models which are often running much weaker hardware specs. The reality is that sometimes devs will only test on their personal iPhones and forget to test on older-gen iPod touches, so the iPod touch experience can sometimes be less than ideal.
Supporting iPod is trivial. If you're using the camera but not checking to make sure one exists first, you're being lazy and sloppy (Apple's docs say this much, though in nicer terms).
Location Services will still work without a GPS, though the accuracy will be reduced since it's relying on WiFi APs.
G+ doesn't use the compass.
On G+ for Android, they allow you to call people from their profile page if a phone # is provided; I assume they have the same feature on the iOS version. Yes, it's an extra few lines of code to determine if the device is a phone and can make calls, but again: lack of this is just laziness.
The iPad is, of course, a different beast, and often calls for a very different UI. Plus I wouldn't be surprised if the G+ website works better in iPad Safari than a native app would, at this point.
Even then, I can't think of much you've got to degrade for the iPod touch. The big stuff (screen/ram/graphics/cpu) is near enough identical. If you support the previous gen iPhone, the current gen iPod should be no problem. You can pick up location from wifi... all I can think of not being available is the compass...
The latest iPod touch does have a camera. It looks like it was an amateur mistake to not include the iPod touch to me. Just because it doesn't have a GPS chip doesn't mean you can't get your location.
The presence/lack of a camera and th compass are differences between iPhones and older iPod Touches.
The "nearby" and photo features seem pretty baked into the Android version. It just may not be worth the wait to condition those features and start the QA process for v.1
That’s stupid, though. iPod touches can competently locate themselves (it’s actually astonishingly precise – at least in cities) even without GPS. Oh, and the app should already behave gracefully when determining the location fails – GPS is most certainly not always available.
iPod touch is generally easier. It usually comes down to gracefully degrading features. Much care must also be taken to ensure that the app performs well on the iPod touch models which are often running much weaker hardware specs. The reality is that sometimes devs will only test on their personal iPhones and forget to test on older-gen iPod touches, so the iPod touch experience can sometimes be less than ideal.