it really just depends what android you get. I've had my droid x for a year now and its as fast and works as well as the day I got it. There are different classes of android phone and if your comparing it with the iphone you should only be considering the high end phones.
Iphones slow down and break just as often as the high end androids.
And for all you people who claim your android has 'broken' i bet you've just bogged the system down with pointless shit. Back-up your contacts, apps, and photos and clear your factory data and cache and it will run like the day you bought it.
If your gonna own a 'smartphone' you need to be a smart owner.
But yea, obviously the iPhone is a great choice. maybe also look into the motorola droid X 2. Same phone I have and love but it's got a duel-core 1 ghz processor and higher density LCD.
Also casio makes a indestructible (G`zone) android that can be submersed 10 meters in water and has a shatter proof screen. My roommate just got it and its really nice. Good option if you like to ski/swim/shower with your phone.