Surprisingly so. I'm actually quite amazed at how smooth and fast it is on the 520's hardware. I've used new-ish Androids with similar configurations (dualcore 512ram) and they've all felt much less snappy.

Considering who's making the OS it's surprising how well it works. I've used portable operating systems from Microsoft in the past (I have a pocketPC that runs WinCE and a Samsung i840 that runs WinMobile) and they've always felt like Microsoft didn't entirely know what they were doing. CE is a massively cut-down version that feels like Windows with just one leg and no arms, and WinMo actually kinda-sorta works but it's a usability mess with an unclear interface.

Not so WP8; the interface works, the software works and since I started using it the whole thing has been - and believe you me, I'm fully aware of how ludicrous this sounds - rock-stable. Seriously, I have yet to see one crash or unexplained slowdown.

The system does have a number of flaws: for instance, it's closed-down to annoying levels (you want a file manager? Nope - there's no way to access the internal filesystem) and subjected to abundant corporate stupidity (installing MapQuest, which is apparently supposed to be unavailable in Europe for reasons unknown to me, required setting the phone's region to the United States and adding an American proxy to the wifi settings).

I still think Android is a better system for phones from low-midrange upwards, because they have enough power and resources to make it work well despite its natively inefficient nature, and once smoothness is achieved Android's main problem goes away and its many advantages utterly crush the competition.

However, for cheap low-end phone hardware I've no doubt that WP is the smoothest, fastest system currently available. Whether that also makes it better for you depends on how much compromise you're willing to tolerate over its closed nature. Me, I'm doing moderately well - but I do get the occasional moment where I want to scream at Microsoft for not giving me anywhere close to the control I'd like over the phone.

Multitasking actually seems to work fairly well. It's not quite as intuitive as it is on a desktop machine or Linux portable, but I haven't had the sort of headaches Android likes to give you in low-RAM environments.

Is there any point in ever upgrading to a 925, considering how well WP8 runs under the 520's hardware? It doesn't seem to need the additional power. Did you feel any difference between the two?

Truth be told, WP is the sort of system you'd give to your mom. It does its job, yes, but that's all it does - there's no way to convince/coerce it into doing anything else. Compare with Android, which can be bludgeoned, hacked and subverted into doing all sorts of unplanned things - if you have the patience and willpower.

I'm also annoyed at the impossibility of using a hardware bluetooth keyboard, as there's no support for external HID devices in WP8. Having a physical 'board would remove one of my biggest gripes with WinPhone - the lack of alternative input methods.

No Android device truly gives its best without a tweaked custom ROM. I've seen horrible clunkers that became very pleasant to use after a reflash.

I disagree. I've used it on a friend's phone, and I consider it the worst of the big three systems currently available. It feels like a mobile OS reimagined by Fisher-Price. Besides, iPhones are far too expensive.