If you’ve selected a graphic file (.bmp, .gif or .jpg), File Viewer can display it as a picture.
Trial Evaluation session will allow you to see only half of the picture, paid users see full picture.

You can see content of plain text files also:

Note: The File Viewer can show only plain text files and simple graphics in a format that looks normal to you. If you select a format that cannot be translated properly, then you will see the file in ‘HEX’ mode, meaning you are seeing the hexadecimal view of the file. If you are not familiar with this format, then you should not preview files other than text files and graphic files. ‘HEX’ mode is for advanced users. Additionally, you may also request 1GB Free which is free quota that you can use to also determine the quality of the found data.

Small toolbar on the File Viewer allows you to choose font, mode (hex, text, formatted text) and codepage for displaying file content.