Twitter has hit the publish button on its new Twitter app for Windows 10, presumably also coming to Windows Phone.
In our short time with the app, we cannot say we are overly impressed but it at least looks okay and does some basic things. For instance, there is no quote RT, no pull to refresh, no settings, no large tile, and no location info.
You do get a search tool and evidently inline GIFs work with a nice little player. Plus you can upload photos. Also, as noted in comments, if you go to your Me tile area, you can see some fine-grained controls for notifications, thankfully.
We'll spend more time with it and see about following up later with more info. The app is likely ideal for very casual users but if you are a power Twitter user, Tweetium is still your best bet.