Just like the new Facebook timeline, Gmail also recently forced their new theme on users and apparently many people are not happy with this decision. While Gmail earlier provided a simple way to revert back the Gmail interface, that option is no longer available. This has definitely not gone down too well with Gmail users.
So is there any way in which you could revert back to the old Gmail interface? Well, not officially, but you can still do it thanks to a Stylish script.
The Return of Old Gmail Stylish script is one which resembles the “Old Gmail” interface the most. Although the overall interface is not as neat (see screenshot above), it definitely is one of the best options if you despise the new Gmail interface. The script in question reverts back some of the Gmail styles to the older one and also reverts back the top navigation in Gmail.
You will also find several other Stylish scripts for Gmail, however, the one listed here seems to be the best alternative to get back the old Gmail interface. You can also try out several other themes for Gmail by using this Stylish search.
Please note that Firefox users will have to install the Stylish add-on before using the scripts. Google Chrome users can also install the Stylish extension or install the Stylish script as a Greasemonkey script and run it as an extension.