This is honestly one of the best firmware’s to use, and anyone that wants to simply make their router better should use this. The installation process is extremely easy.
I use to use DD-WRT after original Tomato stopped being updated for the latest routers for the last few years, until 2012 (and I know slightly longer) were more compatible with the newer routers today without many issues.
In the past, I use to own versions of the Linksys WRT54G and you will find that Tomato is the best custom firmware to put on this router and other compatible ones. You can read all about it at the main website: http://polarcloud.com/tomato.
As posted at the Tomato site, here are alternatives for you to use if you do not want to use Tomato.