have a pixi as my main phone, but been playing with an iphone for a while (got a used 3gs from an old coworker), no service and not jailbroken, running 4.3 (not installing itunes, so i wont b updating it anytime soon) using it on wifi only.
i was completely surprised at how often the apps crash on it. dont really have a large amount of apps, about 20-25, all free apps, majority of which i seldomly use... i mainly use it for aim, 4sq, fb, camera and a few games. do not have any music or videos (besides what ive filmed) on it (dont want itunes on my machine, dont even want to put it on a VM, lol)
i really dislike how iOS keeps every single application you touch open at all times, even after powering down and booting back up. i think the way iOS handles "multitasking" is leading to its instability and overall lag that i've experienced so far.. i have a feeling the home button will be failing at some point in time just because its is the one and only way to do anything on the device. single, double, triple home click = lots of wear n tear... i guess thats why ip5 is going to a touch home button (from rumors on the web).
overall feel, iOS is just clunky, i dont like that i have to poke at everything all the time, makes it feel really unintuitive (more so, it makes me feel like a dumb caveman), even tho it was built for ease of use. for me... ease of use, webos is soooo much easier to use. the keyboard makes getting to contacts, applications, searching so much easier than clicking the home button 3 times on iOS (and the other ways u can configure it) gesture area makes one handed operation so much more fluid and complete.
i cant say too much about android, just played with a few of my friends devices briefly... altho ill be getting a nexus one in a few days to get down n dirty with for a while. not to mention ive been extreeeeeeeemely tempted (dont hurt me k?) by the nexus S coming out may 8th for sprint X) lol