I recently exchanged my old phone and got the T-mobile G2X. I had done a lot of research on the phone because, unlike for many people in this day and age, this was going to be my first smart phone. The smart phone market is so huge now that it is sometimes almost impossible to decide which phone you want. I looked at the three major options: Apple, Microsoft and Google (Android).
I really like the new Microsoft OS. I think the experience is really smooth (although that should be a given on a smartphone) and there are some very interesting and user-friendly design aspects incorporated into the OS. One thing I had against the OS was that it still did not (and does not) run on a 4G device. For me it was not worth it to buy a 3G device with 3G being a relatively old technology. I have also heard people say that the app store for Microsoft is not yet big enough, although this was not the deciding factor for me.
As far as Apple's option goes, I had never been quite as into the iPhone as many other people have. I admit that it is a high-quality product and being a Software Engineer myself, I can vouch for the quality of the iOS. With the biggest app store currently available, this is obviously an option well worth consideration for many.
My choice to go with Google was based on a couple of things. Compared with the Apple strategy of restricting access to anything that's not from the "Apple Realm" I think goes against the whole concept of reaching as many people as possible with your device. I understand that it has its advantages. For instance, from a software standpoint, applications can be tweaked exactly to run extremely well on a very specific set of hardware components. Though that may be, I think Google's open approach is probably paving the way for the future. The Internet giant has taken over Apple with regards to smartphone OS sales an is gaining ground as far as tablets go as well.
More about the G2X: So far I have been very impressed with the phone. It sports a dual-core 1GHz process and is very fast. Since the process is made by Nvidia, the phone's visual quality is excellent. Some people have complained about the battery life of the phone; however I have gotten at least 36 hours off of every charge (while using the phone quite often for online tasks).
I will write more soon, but for now all I can say is that this phone provides for a very smooth experience and will not disappoint!
Hermann