Pros -Fast processor
-Excellent battery life
-Big screen (if you are into that sort of thing)
-Camera takes great pictures
Cons -Screen brightness only has three settings (low, med, high)
-Speaker not loud even at high settings (can't hear it ring in noisy environments)
-Back side of phone scratches/dents easliy
-Windows Phone 8 OS limitations
Summary Not wanting to jump into Apple's ecosystem and tired of manufacturers/carriers not updating Android phones, I decided to give Windows a try. I've had this phone for about three months now and so far I have been impressed. The phone sports a zippy processor, beautiful screen, latest connection standards (including 4G LTE), and a great 8MP back side camera (the front side is alright as well). The battery life is excellent; I can get 3 days (that's right - days!) charge out of it if I'm not constantly on it. Even with heavy use, it can usually get through half that time without breaking a sweat. My previous experience with Samsung phones suggests that the battery life will decrease significantly over the lifetime of the phone, however since the battery is replaceable I can just replace it with a new onew when it can't hold a good charge anymore. Call quality is also good, but that probably has more to do with the network.
As for the downsides, for some reason there are only three brightness settings on the phone (low, medium, and high), whereas most other phones have 'spectum' style brightness adjustment. I personally like to have my brightness set to somewhere between medium and low, but alas, it cannont be done on the Ativ S. The speaker is also a bit of an issue; I've found it to be fairly quiet even at a high setting, and have missed a couple of calls while moving through noisy environments. Even though I haven't dropped it (and hopefully never will) I've noticed the phone has picked up a couple of scratches on the back side just from being on tables/in my pocket. The back side looks like brushed metal, but it is actually a metallic looking plastic cover.
Although I do not want to make a Windows Phone 8 review here, a phone is only as good as its operating system, and the WP8 OS definitely places some limitiations on what you can do. I actually like WP8; it does a better job of cloud and social network integration than any of the other OS's out there, and you can't get much better productivity with Microsoft Office baked in. However, there are still some issues. I don't consider myself a heavy app user, but even I have been surprised by the limited selection of apps in the Windows Store. There is also far less customization options (when comapred with Android) as well as some issues with the notification system that Microsoft still needs to iron out. That being said, WP8 is a very young operating system and most of the issues will be fixed with time and updates. I suggest you look at CNET's WP8 review.
Overall, this is a great phone that has served me well so far. If you are looking to make the jump to Windows Phone, this phone will be an excellent buy.