Notably, the look of Cortana doesn't represent the final shipping product. The UI isn't finished. It will likely look much better when unveiled to the public.
From the get go, Cortana can do pretty much everything the Windows Phone version can. This includes reminders, call people with skype, check my location/maps, play/pause music, launch apps, check the weather and more. Right now, Cortana doesn't have a personality in Windows 10, meaning she doesn't answer questions like "Who are you", however we have it on good authority that she will have this ability by the time she rolls out to the public.
Take a look at the video below. For more details on the upcoming release of Windows 10, click here.