I also have a Lumia 800. At the time when I got it I thought Android generally looked a bit sluggish and 'unpolished', and Samsung phones looked cheap and tacky (sorry folks, but I still think they do now). As for iPhones, a Crapple product was out of the question! Windows Phone 7 ran smoothly and looked stylish, and I really liked the design and weight of an 800 we had on trial at work.
That choice did come with quite a few downsides, though most of them relate to the operating system rather than the hardware. There are quite a few features that phones that came before it had that it lacks. It's really stupid stuff like having to use Zune to transfer files to and from it (what's wrong with treating it as a mass storage device?) and a disregard for customisation. For instance, creating your own ringtone is a real pain, and you can forget custom text alerts! Communication from Microsoft on updates is terrible too; the Windows Phone 7.8 update was announced half way through last year, but barely anything about it was revealed until recently and it still hasn't been released!
The above paragraph probably paints a false picture of my view on the phone, as despite those gripes I've been very pleased with it on the whole. I like messing about with technology, but I view phones as functional devices and the 800 does all the usual stuff well. Battery life in particular has been a pleasant surprise. I'm not glued to my phone like some people are, so perhaps that's why it'll go for about 3 days between charges.
If I were to replace it now I'd either be looking at a Lumia 920 or Nexus 4. Nice as the 920 is, if Windows Phone 8 is as restrictive as 7 I'd probably go for the Nexus. Android 4.2 on my Nexus 7 took a bit of getting used to, but I really like it now and would be happy to use it on a phone that feels well put together.