Since our (I'm still on a family plan with my parents at the moment) contract with Sprint expired two years ago, we finally decided to change carriers and decided on AT&T (I know not the best of decisions but they had the best deal when it comes to price). So when it came down to choosing a phone, I kinda had a dilemma on my hands. On the one hand, I really like Android, but there aren't really any good Android phones for AT&T. I considered iPhone 4 for a second, and, well, that was that. After seeing a lot about WP7 and watching the interface in action, it really intrigued me after after playing around with the Samsung Focus for a little bit in the AT&T store, I decided to go with the Focus and WP7. Here are some of my thoughts on the phone as well as the OS: 
 
First off, the Focus is a pretty damn good phone for the most part. The outside feels a little plasticky but also feels very sturdy. The super-amoled screen is as gorgeous as advertised and looks absolutely amazing. The quality of the camera and the phone calls themselves are also top notch (though the focus on the camera isn't the greatest around, the picture quality is excellent) and the sound quality when playing music or videos is pretty good as well. The touch screen is also very responsive and the on-screen keyboard is one of the best I've used (once you get used to it). The main gripe I have about the phone is that the adding a micro-SD card required me to reset the phone, meaning it wiped all the data including media and apps. Now this wasn't a big deal for me since I had only been using the phone for a couple of days before I added a 16GB card, but if I ever wanted to upgrade to a 32GB card, I'd have to re-sync all the data on the phone and re-download all my apps again. Not a huge hassle, but a definite pain. Battery life has been pretty good so far (it'll last a typical 8 hour work day if you don't spend too much time on the internet or watching videos), though it definitely needs to be plugged in and charged every night (especially since I'm using it for music as well as wifi).
 
As for the WP7 OS itself, overall it feels very good, though it obviously suffers from a lack of certain features like copy-paste for instance (some of which will be added with upcoming updates). One thing that stands out is the UI. The "tile" system it uses for the main screen is a little unconventional but also feels very fluid and is highly customizable. The app browser, while it can crash now and then, has a good-looking interface but browsing it can be somewhat of a hassle and the search function is also somewhat poorly implemented (though there are apps available to fix that). Also despite some people complaining about the lack of an "autoupdate" feature for apps, I don't see why this is a bad thing unless you're not much of a PC user. I never have Windows Update setting to "auto" on my PC nor do I use the autoupdate feature that many PC games have nowadays. But maybe that's just me. The media player also looks and feels very good, but I do wish it had some more advanced features (i.e. a "now playing" section would be nice, rather than just having a "history" section; and I'd also like to be able to view info about my music and videos). The built-in IE browser works well enough, though it doesn't support flash. Having Office applications like Word and Excel is also pretty neat (it has already proven very useful during some of my clinical rotations). The Xbox-live integration is also pretty neat, but the actual app itself can be a little laggy. Still, I definitely like the idea, so I'm hoping that Microsoft will add more features to it in the future. The apps themselves are somewhat of a mixed bag (as they always are) but given that the OS has only been out for a few months, it's not a big surprise. Still there are already some great apps available, and some, like the awesome Netflix app, are pretty good. It seems like Microsoft put a lot of focus on social-networking when they designed WP7 and features like the built-in Facebook integration show it. I'm personally not a huge facebook user, but being able to sync my Facebook profile right out of the box is a nice, if not necessary feature. 
 
It definitely seems like Microsoft wanted to veer away from the more tech-savy and geeky Android platform (i.e. blocking native code) and opted for a more user-friendly experience. And while I applaud them for opting for greater usability as opposed to a more advanced feature set, I would have liked to see some of the geekier features that Android OS has. Despite that however, I'm still pretty pleased with the phone an the OS as WP7 does seem to have a lot of untapped potential. The question is whether or not Microsoft will actively support the platform, especially when they decide to roll out WP8. 
  

Sounds about what I expected, good framework but still very 'first gen' feeling.

My main worry is also if they will continue the support also. Microsoft has been very un-supportive of their platforms. Except for the 360 of course because it's a money maker. Too bad their phones didn't sell very well.

" @spazmaster666: Have you had any issues with viewing the screen while using the phone outside?  One of my older phones and my Zune HD had AMOLED screens and would get completely washed out in the light.  I too hope Microsoft continues to support this platform because I think it has a lot of potential, but I'm not quite ready to switch phones just yet. "

I too have the Focus, and I've been enjoying it so far. It's definitely one of the better "1st gen" phones released, and I'm anxious for the direction Microsoft will take it. The Zune software for the computer took a little getting used to, but it works. I love being able to upload the Bombcasts wirelessly.

@spazmaster666:  I had to choose between the iPhone 4 and the Samsung Focus with WP7, Focus won me over. I really  like the Focus because for the apps I have on it and for my work flow, that thing is stupid fast.. Especially after using the  iPhone OS for about 3 years, it was a good change. The bad thing is, I lose the functions of the apps that are not yet in the Zune Marketplace and for some I have to repurchase to add it on the phone. I still haven't bought the extra memory, I am looking forward in wiping the phone just to resync  then I decide to buy the upgrade. I am still waiting for that copy paste function myself.