So a 2010 Honda Civic is superior to a 1908 Model T Ford and a 2020 Honda Civic can't be any better? Interesting.

Slight exaggeration aside, the following is coming from someone who has never handled an N900 and who owns two iPod Touches (1g and 3g):

Nokia N900
+ FM Transmitter
+ IR Transmitter
+ Hardware Keyboard
+ Memory Card Slot
+ Kickstand
+ 2 stage (I think, see above) camera button
+ Removable battery
+ Fine point stylus compatible (a must for some people)
+ Flash support (until HTML5 has an official, or at least universally implemented, open-source video format, Flash is better)

iPhone 4
- Updates break jailbreak
- Tethered to iTunes (hard-locked until first sync. Also "syncing" is a bit of a misnomer here, if something isn't checked to sync for a particular syncing, but rechecked in the future, it doesn't sync, instead iTunes overwrites what's on the iPhone. Not what I would call "syncing")
- Ethical Issues (although it's possible that Nokia does something similar): With refunds, developers return 100% of the app's price, despite only having been paid 70%. Apple keeps the other 30%. Although that doesn't apply to jailbreak apps, obviously. And developers don't mind, apparently.
- Mobile Safari has difficulty not crashing.
- Although jailbreaking has been declared legal, Apple appears to be attempting to find another way to prevent/kill jailbreaking
- Based on how Apple treats them, Apple seems to believe that iOS users are criminals of limited intelligence that should be put in asylums under guard.

I think the big problem for a lot of people (at least for me) is simply the environment that Apple cultivates around iOS, as mentioned in the last point under iPhone 4. Keep in mind that if your cousin is incapable of comprehending that different people can have different wants/needs, then he is also incapable of making a valid argument.