It certainly makes it a lot easier to find cheaper tickets by fiddling with urls, varying times, routes and breaking journeys. The mobile site is really good too and loads really nicely on my phone, but doesn't quite have the full featureset.
The one problem with the site is the lack of support for young persons railcard in finding cheap tickets. I'm not sure you can easily get the right data to fix that though.
Another site for finding nice routes is the Association of Train Operators route guides which have been recently released in pdf format. It's particularly useful alongside traintimes.org.uk to find good places to break a journey to save money.