Windows Phone 7 vs iPhone 4

Okay I know I'm going to get the "take it the Tested forums" guy in here but I'd actually like to get some GB user's opinions about this. I was wondering if anybody has had experience with either or even both of these phones and which of the two you'd recommend, I'm seriously considering the Samsung Omnia 7 but again I'm not too sure.

I don't have any problems with iPhone, it does everything I would want it to do, and very well. I haven't used a windows 7 mobile device, though.

" I don't have any problems with iPhone, it does everything I would want it to do, and very well. I haven't used a windows 7 mobile device, though. "

It depends. If you use a lot of Microsoft products and services, probably go for Windows Phone. If your invested in the Apple ecosystem, then go for the iPhone. Both platforms handle 3rd party services like Google accounts just fine. Also, keep in mind that Windows Phone 7 is actually a brand new platform for Microsoft so it is less mature than the iPhone ecosystem as of now, although the app ecosystem is already growing at an impressive rate. 

I am on my second iPhone, I have also had a Win Mobile 4 and use a Win Mobile 6.1 phone for work. I have yet to have a good Win Mobile experience, but I have also yet to experience Win Mobile 7 which is not an incremental revision but a completely new OS with much higher hardware requirements, so the spec on the device should be a lot higher than many smart phones running Android or early versions of Win Mobile. Before Win Mobile 7 I would have said just get an iPhone, right now I would say look at as many YouTube video reviews as you can and try and get a demo in a shop as well.
 
There seem to be a lot of positive noises being made about this phone and I think Microsoft have worked really hard to find out what people really want from a Smart Phone and deliver exactly this. I'm still not ready to part with my iPhone though.

" I don't have any problems with iPhone, it does everything I would want it to do, and very well. I haven't used a windows 7 mobile device, though. "

Windows Phone 7 is a developing platform, and if you buy in, know that you're buying into a platform with an uncertain future as a first generation user. It has some features missing that both iOS and Android have, and you shouldn't be surprised if the experience isn't quite as smooth. 
 
With that said, I recently switched over from Android to a Samsung Focus (I've got experience with all iOS as well), and I'm really liking it. Additionally, Microsoft's shown a clear dedication to iterating the hell out of it, and they've got a  massive marketing budget; overall, I feel good about the future. I really enjoy how, once you get used to the software (I used a Zune HD prior, which I switched to from an iPod Touch, so I had some familiarity with the UI), it becomes incredibly easy to access all of your essential data. It's still not perfect: hub integration could be better, apps take a bit long to launch, and the market is a bit rough, but if you're interested, and know that you're buying into a new, still developing platform that isn't assured of success, then I'd say go for it.

I am on a HTC Mozart WP7 phone, and quite enjoying it. As mentioned by @jukezypoo it is developing. The apps aren't quite there yet, but I love the Zune platform and I use SharePoint a fair bit. 
 
Plus I can get achievements on the bus!