The iPhone App store has a frankly stupid number of apps on it and, outside a specific set of things they ban for a variety of reasons (porn, things that break carrier agreements, some stupid reasons that make no sense) you'll probably always find there is indeed ' an app for that'.
iPhones seem to have very good resale value
They are however a bit 'dull' - due to the massive media exposure even the iphone 4 doesn't really have a lot of 'cache' to it any more. Very few people will probably bug you to have a go of your iPhone these days.
Exchange support is indeed good but it does seem to have the odd bug or two from what we've seen.
Android phones are very good - generally most of them are as good or better than an iPhone. However the OS situation is a bit of a mess; some phones have different versions of the OS than others, which means some apps work on some models of phone but not others. Also the UI is not standardised, which means some are better than others. In most of them, once you stray away from the obvious functions things can get a bit 'geeky' - I'd say Android is still behind the iPhone in sheer user friendliness terms. A good Android phone is as good as an iPhone for less money usually, but you'll need to do research to make sure you're getting a good one, whereas with the iPhone you know exactly what you're going to get regardless of which model you buy.
The Android App store is smaller than the iPhone one but is probably busier and has a higher percentage of apps which are free. Quite a lot of them are very good and those that are are much more likely to be free than on the iPhone store, however the open nature means some of them are pretty bad and even, in the odd case, outright nasty.
Android phones are still unusual enough to have some curiosity value - if exclusivity is an issue, an android phone will be better than even an iPhone 4.
If you get one of the ones with the newer OS on it, Exchange works well. if you get one of the ones with the older OS version on it, it doesn't work at all, despite what anyone may tell you.
Absolutely, utterly awful. You know the old maps that had a sign on the unexplored ocean that said 'here be dragons'? Just like that. Stay Away. I don't know anyone whose used one of our work Windows mobile phones who either hasn't dumped it for an iPhone/blackberry/android or is going to the first chance they get. We've had more than a few winmo phones been 'accidentally dropped' onto hard surfaces. from a distance. With force. However, if you desperately want exchange connections to work as well as possible and this is the only overriding factor in your purchase decision, then maybe give one a try. But be prepared to swear at it, often.
Jon
