Great fun, but plagued by stability problems.
Many strategy games take hours or days to play, but you can have a fun game of Railroads in about an hour and feel a sense of accomplishment. It's great for when you don't want to sit down to a lengthy session of the Civilization, Sim City or Total War type games but still want to use your gray matter.
Unfortunately the game has had stability problems, though this seems system dependent. Fortunately there is an autosave feature, so you can be back up and running fairly quickly. I personally have found that it benefits from lots of RAM and a fast processor. Don't assume that you'll get better frame rates just by upgrading your graphics card.