Sony RAW files inherently have a very small embedded preview. This means that Select and other software are only able to show you a low-resolution preview of your image. So, when you zoom in you'll see a somewhat pixelated image. You can import Sony .ARW files into Select, but they will be low quality. However, we have a solution...
When you shoot with a Sony camera, make sure you are shooting on the RAW+JPG setting, with the size set to Large/Fine. When you take a shot, your camera will create a .ARW file and a .JPG file with the same name. When you import into Select we will actually show you the .JPG file (which is high resolution) so you can zoom in and see full detail. When you rate the image we will create an .XMP sidecar file to store your rating so that when you ship into Lightroom to edit your .ARW file will also have your rating associated to it.
If you don't want to shoot RAW+JPG, or you want to review a shoot where you did not have this setting switched on, you can still see high res images in Select. To do this, convert your .ARW files into .DNG files with high resolution embedded preview using Adobe Lightroom or another program. You can now import them into Select.
We are working on a way to derive our own high-resolution previews out of Sony files, however, this is pretty tricky to do fast so it might take a while for us to get there!