With the cancellation of MSTS2 by Microsoft, RS.com - who now own the rights to the Rail Simulator franchise - have been given an ideal opportunity to become the foremost train sim developer/publisher. Railworks is their first retail release which attempts to tidy up the state of affairs inherited from Kuju and EA. Available either via Steam or the DVD version (point of interest, on an "ecodisc" which is a flimsier version of the conventional DVD) Railworks consolidates the previously seperate UK and US versions, some new content and a few enhancements. As pointed out in earlier reviews, the DVD version also requires Steam to be installed as a kind of copy protection but this is far less insidious than some other forms of copy protection.
Graphically, Railworks is similar to Rail Simulator but there have been enhancements to lighting and other effects. Don't expect Oblivion or Crysis level of detail but the world seems to look more lifelike. Sound is pretty much the same though the traction sound provided for the new locos - Class 37, DB V200 and US F7 are all excellent. AI and signalling has been the subject of heated argument on several of the train sim forums. This is one area of the core simulation which still needs improvement and RS.com are I'm sure quite aware of this from the many comments posted on the matter. One advantage of using the Steam system is that updates can be distributed relatively easily, along of course with any new official content.
Railworks incorporates the Developer Tools which previously had to be applied for and downloaded seperately. It should be noted though that the sandbox process to create new routes and scenarios is still fairly complex and aimed at power users.
With support from the user community I'm hopeful that the rebirth of Rail Simulator into Railworks will keep the train sim genre going for the forseeable future, given that the closest competitors (MSTS & Trainz) are both creaking along on 8 year old code and graphics engines.