I just updated my router (Linksys WRT54GL) with the Tomato Firmware. Here are my initial observations:

  1. The upgrade was much faster and easier than I was anticipating. After writing down some settings I had with the default firmware, I flashed the router. A couple minutes later, I was in the tomato interface completing the last of the installation steps and configuring my wireless network.
  2. The first thing I noticed was that my laptop (connected via wifi) is noticeably faster loading web pages. I think it had been having trouble with DNS lookups. I don't know exactly what is different now, but that was a nice bonus.
  3. I boosted the wireless transmit power (from 42 to 84 dB), and am now (finally) able to get wifi throughout my house. I walked to the farthest corners of my house and still had a very usable connection.

I haven't yet played with the more advanced settings (other than boosting wifi power), but so far I am quite impressed.