What's going to cause some major headaches, and major criticism, is that the app does not allow calling if Skype is open and the user is in the app.
Reportedly, the reasons are not arbitrary. A Skype spokesperson said the omission is due to "a combination of how Skype works and how the Windows Phone OS works."
If that's the case, technical limitations, it's most likely on the Windows Phone side of things, and shows that Windows Phone still needs to mature when compared to iOS and Android.
There are some minor improvements to the Skype 1.0 release. Among them are the ability to search for and add new contacts. Other changes include necessary bug fixes, an improved launch time, and the ability to call landlines.
Skype also has versions for iPhone, Android and even Blackberry OS.