As Mary Jo wrote yesterday, Skype for Windows Phone moved from the beta version to a 1.0 release. While it is good to see the application moving forward, there is at least one major limitation that makes the app almost useless on a mobile phone.
Skype 1.0 for Windows Phone lets you make Skype video and voice calls over 3G and WiFi, seach for and add contacts, and make calls to landlines. However, no one can call you via Skype unless you have the app open and running on your phone. Unlike Android and iOS, Skype needs to be your active app in order to receive calls as there is no background functionality at all in the app. Tango video calling service supports running in the background so if video calling is important to you then try that service out.
Limitations like this in apps are one reason I am primarily back to using my Samsung Galaxy Nexus with my T-Mobile SIM. I am having a great time with Android at the moment on a number of devices (Samsung Galaxy Nexus, HTC One X, and HTC Flyer) and could see myself going just with Android as my personal mobile platform.
Even though Microsoft now owns Skype, Mary Jo pointed out that the plan for Windows Phone 8 is to still have Skype as a stand alone application. Microsoft has the potential to do great things with Windows Phone, but there is still a LOT of work to do.