Firstly let's focus on the design. All options are now on the right instead of below the Minecraft News window. It has a dropdown menu allowing you to select what version of Minecraft you want to launch - very similar to Technic's options. Right now the only option is the snapshot, those wishing to run Minecraft 1.5 will have to use the old one. Right now there is only a fraction of functionality that other launchers offer - but on par with the classic one.
When the Play button is clicked, you can see all the files being downloaded one by one, which should make debugging much easier. One thing I noticed was that you cannot re-download Minecraft straight from the launcher - you will have to clear your Minecraft files manually for now. We will give you updates on when newer features land in the new launcher, so stay tuned!